[PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Punit Agrawal]

On failing to migrate a page, soft_offline_huge_page() performs the
necessary update to the hugepage ref-count. When
!hugepage_migration_supported() , unmap_and_move_hugepage() also
decrements the page ref-count for the hugepage. The combined behaviour
leaves the ref-count in an inconsistent state.

This leads to soft lockups when running the overcommitted hugepage test
from mce-tests suite.

Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
soft offline: 0x83ed600: migration failed 1, type
1fffc00000008008 (uptodate|head)
INFO: rcu_preempt detected stalls on CPUs/tasks:
 Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
  (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
  thugetlb_overco R  running task        0  2715   2685 0x00000008
  Call trace:
  [<ffff000008089f90>] dump_backtrace+0x0/0x268
  [<ffff00000808a2d4>] show_stack+0x24/0x30
  [<ffff000008100d34>] sched_show_task+0x134/0x180
  [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
  [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
  [<ffff000008143a3c>] update_process_times+0x34/0x60
  [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
  [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
  [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
  [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
  [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
  [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
  [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
  [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
  [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0

Fix this by dropping the ref-count decrement in
unmap_and_move_hugepage() when !hugepage_migration_supported().

Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Christoph Lameter <cl@linux.com>

--
Hi Andrew,

We ran into this bug when working towards enabling memory corruption
on arm64. The patch was tested on an arm64 platform running v4.12-rc2
with the series to enable memory corruption handling[0].

Please consider merging as a fix for the 4.12 release.

Thanks,
Punit

[0] https://www.spinics.net/lists/arm-kernel/msg581657.html
---
 mm/migrate.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 89a0a1707f4c..187abd1526df 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1201,10 +1201,8 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 	 * tables or check whether the hugepage is pmd-based or not before
 	 * kicking migration.
 	 */
-	if (!hugepage_migration_supported(page_hstate(hpage))) {
-		putback_active_hugepage(hpage);
+	if (!hugepage_migration_supported(page_hstate(hpage)))
 		return -ENOSYS;
-	}
 
 	new_hpage = get_new_page(hpage, private, &result);
 	if (!new_hpage)
-- 
2.11.0

[PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Punit Agrawal]

On failing to migrate a page, soft_offline_huge_page() performs the
necessary update to the hugepage ref-count. When
!hugepage_migration_supported() , unmap_and_move_hugepage() also
decrements the page ref-count for the hugepage. The combined behaviour
leaves the ref-count in an inconsistent state.

This leads to soft lockups when running the overcommitted hugepage test
from mce-tests suite.

Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
soft offline: 0x83ed600: migration failed 1, type
1fffc00000008008 (uptodate|head)
INFO: rcu_preempt detected stalls on CPUs/tasks:
 Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
  (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
  thugetlb_overco R  running task        0  2715   2685 0x00000008
  Call trace:
  [<ffff000008089f90>] dump_backtrace+0x0/0x268
  [<ffff00000808a2d4>] show_stack+0x24/0x30
  [<ffff000008100d34>] sched_show_task+0x134/0x180
  [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
  [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
  [<ffff000008143a3c>] update_process_times+0x34/0x60
  [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
  [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
  [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
  [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
  [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
  [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
  [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
  [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
  [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0

Fix this by dropping the ref-count decrement in
unmap_and_move_hugepage() when !hugepage_migration_supported().

Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Christoph Lameter <cl@linux.com>

--
Hi Andrew,

We ran into this bug when working towards enabling memory corruption
on arm64. The patch was tested on an arm64 platform running v4.12-rc2
with the series to enable memory corruption handling[0].

Please consider merging as a fix for the 4.12 release.

Thanks,
Punit

[0] https://www.spinics.net/lists/arm-kernel/msg581657.html
---
 mm/migrate.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 89a0a1707f4c..187abd1526df 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1201,10 +1201,8 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 	 * tables or check whether the hugepage is pmd-based or not before
 	 * kicking migration.
 	 */
-	if (!hugepage_migration_supported(page_hstate(hpage))) {
-		putback_active_hugepage(hpage);
+	if (!hugepage_migration_supported(page_hstate(hpage)))
 		return -ENOSYS;
-	}
 
 	new_hpage = get_new_page(hpage, private, &result);
 	if (!new_hpage)
-- 
2.11.0

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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[PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Punit Agrawal]

On failing to migrate a page, soft_offline_huge_page() performs the
necessary update to the hugepage ref-count. When
!hugepage_migration_supported() , unmap_and_move_hugepage() also
decrements the page ref-count for the hugepage. The combined behaviour
leaves the ref-count in an inconsistent state.

This leads to soft lockups when running the overcommitted hugepage test
from mce-tests suite.

Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
soft offline: 0x83ed600: migration failed 1, type
1fffc00000008008 (uptodate|head)
INFO: rcu_preempt detected stalls on CPUs/tasks:
 Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
  (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
  thugetlb_overco R  running task        0  2715   2685 0x00000008
  Call trace:
  [<ffff000008089f90>] dump_backtrace+0x0/0x268
  [<ffff00000808a2d4>] show_stack+0x24/0x30
  [<ffff000008100d34>] sched_show_task+0x134/0x180
  [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
  [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
  [<ffff000008143a3c>] update_process_times+0x34/0x60
  [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
  [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
  [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
  [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
  [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
  [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
  [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
  [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
  [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0

Fix this by dropping the ref-count decrement in
unmap_and_move_hugepage() when !hugepage_migration_supported().

Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Cc: Christoph Lameter <cl@linux.com>

--
Hi Andrew,

We ran into this bug when working towards enabling memory corruption
on arm64. The patch was tested on an arm64 platform running v4.12-rc2
with the series to enable memory corruption handling[0].

Please consider merging as a fix for the 4.12 release.

Thanks,
Punit

[0] https://www.spinics.net/lists/arm-kernel/msg581657.html
---
 mm/migrate.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 89a0a1707f4c..187abd1526df 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1201,10 +1201,8 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
 	 * tables or check whether the hugepage is pmd-based or not before
 	 * kicking migration.
 	 */
-	if (!hugepage_migration_supported(page_hstate(hpage))) {
-		putback_active_hugepage(hpage);
+	if (!hugepage_migration_supported(page_hstate(hpage)))
 		return -ENOSYS;
-	}
 
 	new_hpage = get_new_page(hpage, private, &result);
 	if (!new_hpage)
-- 
2.11.0

Re: [PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Andrew Morton]

On Wed, 24 May 2017 16:47:28 +0100 Punit Agrawal <punit.agrawal@arm.com> wrote:

> On failing to migrate a page, soft_offline_huge_page() performs the
> necessary update to the hugepage ref-count. When
> !hugepage_migration_supported() , unmap_and_move_hugepage() also
> decrements the page ref-count for the hugepage. The combined behaviour
> leaves the ref-count in an inconsistent state.
> 
> This leads to soft lockups when running the overcommitted hugepage test
> from mce-tests suite.
> 
> Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
> soft offline: 0x83ed600: migration failed 1, type
> 1fffc00000008008 (uptodate|head)
> INFO: rcu_preempt detected stalls on CPUs/tasks:
>  Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
>   (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
>   thugetlb_overco R  running task        0  2715   2685 0x00000008
>   Call trace:
>   [<ffff000008089f90>] dump_backtrace+0x0/0x268
>   [<ffff00000808a2d4>] show_stack+0x24/0x30
>   [<ffff000008100d34>] sched_show_task+0x134/0x180
>   [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
>   [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
>   [<ffff000008143a3c>] update_process_times+0x34/0x60
>   [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
>   [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
>   [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
>   [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
>   [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
>   [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
>   [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
>   [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
>   [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0
> 
> Fix this by dropping the ref-count decrement in
> unmap_and_move_hugepage() when !hugepage_migration_supported().
> 
> Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
> Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
> Cc: Christoph Lameter <cl@linux.com>

32665f2bbfed was three years ago.  Do you have any theory as to why
this took so long to be detected?  And do you believe a -stable
backport is warranted?

Re: [PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Andrew Morton]

On Wed, 24 May 2017 16:47:28 +0100 Punit Agrawal <punit.agrawal@arm.com> wrote:

> On failing to migrate a page, soft_offline_huge_page() performs the
> necessary update to the hugepage ref-count. When
> !hugepage_migration_supported() , unmap_and_move_hugepage() also
> decrements the page ref-count for the hugepage. The combined behaviour
> leaves the ref-count in an inconsistent state.
> 
> This leads to soft lockups when running the overcommitted hugepage test
> from mce-tests suite.
> 
> Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
> soft offline: 0x83ed600: migration failed 1, type
> 1fffc00000008008 (uptodate|head)
> INFO: rcu_preempt detected stalls on CPUs/tasks:
>  Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
>   (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
>   thugetlb_overco R  running task        0  2715   2685 0x00000008
>   Call trace:
>   [<ffff000008089f90>] dump_backtrace+0x0/0x268
>   [<ffff00000808a2d4>] show_stack+0x24/0x30
>   [<ffff000008100d34>] sched_show_task+0x134/0x180
>   [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
>   [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
>   [<ffff000008143a3c>] update_process_times+0x34/0x60
>   [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
>   [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
>   [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
>   [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
>   [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
>   [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
>   [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
>   [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
>   [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0
> 
> Fix this by dropping the ref-count decrement in
> unmap_and_move_hugepage() when !hugepage_migration_supported().
> 
> Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
> Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
> Cc: Christoph Lameter <cl@linux.com>

32665f2bbfed was three years ago.  Do you have any theory as to why
this took so long to be detected?  And do you believe a -stable
backport is warranted?

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Andrew Morton]

On Wed, 24 May 2017 16:47:28 +0100 Punit Agrawal <punit.agrawal@arm.com> wrote:

> On failing to migrate a page, soft_offline_huge_page() performs the
> necessary update to the hugepage ref-count. When
> !hugepage_migration_supported() , unmap_and_move_hugepage() also
> decrements the page ref-count for the hugepage. The combined behaviour
> leaves the ref-count in an inconsistent state.
> 
> This leads to soft lockups when running the overcommitted hugepage test
> from mce-tests suite.
> 
> Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
> soft offline: 0x83ed600: migration failed 1, type
> 1fffc00000008008 (uptodate|head)
> INFO: rcu_preempt detected stalls on CPUs/tasks:
>  Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
>   (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
>   thugetlb_overco R  running task        0  2715   2685 0x00000008
>   Call trace:
>   [<ffff000008089f90>] dump_backtrace+0x0/0x268
>   [<ffff00000808a2d4>] show_stack+0x24/0x30
>   [<ffff000008100d34>] sched_show_task+0x134/0x180
>   [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
>   [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
>   [<ffff000008143a3c>] update_process_times+0x34/0x60
>   [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
>   [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
>   [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
>   [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
>   [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
>   [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
>   [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
>   [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
>   [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0
> 
> Fix this by dropping the ref-count decrement in
> unmap_and_move_hugepage() when !hugepage_migration_supported().
> 
> Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
> Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
> Cc: Christoph Lameter <cl@linux.com>

32665f2bbfed was three years ago.  Do you have any theory as to why
this took so long to be detected?  And do you believe a -stable
backport is warranted?

Re: mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Manoj Iyer]

On Wed, 24 May 2017, Punit Agrawal wrote:

> On failing to migrate a page, soft_offline_huge_page() performs the
> necessary update to the hugepage ref-count. When
> !hugepage_migration_supported() , unmap_and_move_hugepage() also
> decrements the page ref-count for the hugepage. The combined behaviour
> leaves the ref-count in an inconsistent state.
>
> This leads to soft lockups when running the overcommitted hugepage test
> from mce-tests suite.
>
> Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
> soft offline: 0x83ed600: migration failed 1, type
> 1fffc00000008008 (uptodate|head)
> INFO: rcu_preempt detected stalls on CPUs/tasks:
> Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
>  (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
>  thugetlb_overco R  running task        0  2715   2685 0x00000008
>  Call trace:
>  [<ffff000008089f90>] dump_backtrace+0x0/0x268
>  [<ffff00000808a2d4>] show_stack+0x24/0x30
>  [<ffff000008100d34>] sched_show_task+0x134/0x180
>  [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
>  [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
>  [<ffff000008143a3c>] update_process_times+0x34/0x60
>  [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
>  [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
>  [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
>  [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
>  [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
>  [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
>  [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
>  [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
>  [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0
>
> Fix this by dropping the ref-count decrement in
> unmap_and_move_hugepage() when !hugepage_migration_supported().
>
> Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
> Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
> Cc: Christoph Lameter <cl@linux.com>
> ---
> Hi Andrew,
>
> We ran into this bug when working towards enabling memory corruption
> on arm64. The patch was tested on an arm64 platform running v4.12-rc2
> with the series to enable memory corruption handling[0].
>
> Please consider merging as a fix for the 4.12 release.
>
> Thanks,
> Punit
>

I applied this patch applied to Ubuntu Zesty (4.10) kernel and tested on 
QDF2400 platform with mce-test without config migration enabled.

== dmesg ==
[   91.569358] Soft offlining page 0x1763c00 at 0x400000000000
[   91.569364] soft offline: 0x1763c00: migration failed 1, type 
100000000008008
[  150.282911] Soft offlining page 0x1763c00 at 0x400000000000
[  150.282917] soft offline: 0x1763c00: migration failed 1, type 
100000000008008

The mce-test failed as expected but did not encounter the soft lockups. 
(The test case might have an error it is missing an 'echo' in failure 
case.)

$ sudo ./run_hugepage_overcommit.sh

***************************************************************************
Pay attention:

This test checks that hugepage soft-offlining works under overcommitting.
***************************************************************************


-------------------------------------
TestCase ./thugetlb_overcommit 1
FAIL: migration failed.
Unpoisoning.

 	Num of Executed Test Case: 1	Num of Failed Case: 1

Tested-By: Manoj Iyer <manoj.iyer@canonical.com>

Thanks
Manoj Iyer

> [0] https://www.spinics.net/lists/arm-kernel/msg581657.html
> ---
> mm/migrate.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 89a0a1707f4c..187abd1526df 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1201,10 +1201,8 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
> 	 * tables or check whether the hugepage is pmd-based or not before
> 	 * kicking migration.
> 	 */
> -	if (!hugepage_migration_supported(page_hstate(hpage))) {
> -		putback_active_hugepage(hpage);
> +	if (!hugepage_migration_supported(page_hstate(hpage)))
> 		return -ENOSYS;
> -	}
>
> 	new_hpage = get_new_page(hpage, private, &result);
> 	if (!new_hpage)
>

--
============================
Manoj Iyer
Ubuntu/Canonical
ARM Servers - Cloud
============================

Re: mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Manoj Iyer]

On Wed, 24 May 2017, Punit Agrawal wrote:

> On failing to migrate a page, soft_offline_huge_page() performs the
> necessary update to the hugepage ref-count. When
> !hugepage_migration_supported() , unmap_and_move_hugepage() also
> decrements the page ref-count for the hugepage. The combined behaviour
> leaves the ref-count in an inconsistent state.
>
> This leads to soft lockups when running the overcommitted hugepage test
> from mce-tests suite.
>
> Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
> soft offline: 0x83ed600: migration failed 1, type
> 1fffc00000008008 (uptodate|head)
> INFO: rcu_preempt detected stalls on CPUs/tasks:
> Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
>  (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
>  thugetlb_overco R  running task        0  2715   2685 0x00000008
>  Call trace:
>  [<ffff000008089f90>] dump_backtrace+0x0/0x268
>  [<ffff00000808a2d4>] show_stack+0x24/0x30
>  [<ffff000008100d34>] sched_show_task+0x134/0x180
>  [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
>  [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
>  [<ffff000008143a3c>] update_process_times+0x34/0x60
>  [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
>  [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
>  [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
>  [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
>  [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
>  [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
>  [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
>  [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
>  [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0
>
> Fix this by dropping the ref-count decrement in
> unmap_and_move_hugepage() when !hugepage_migration_supported().
>
> Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
> Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
> Cc: Christoph Lameter <cl@linux.com>
> ---
> Hi Andrew,
>
> We ran into this bug when working towards enabling memory corruption
> on arm64. The patch was tested on an arm64 platform running v4.12-rc2
> with the series to enable memory corruption handling[0].
>
> Please consider merging as a fix for the 4.12 release.
>
> Thanks,
> Punit
>

I applied this patch applied to Ubuntu Zesty (4.10) kernel and tested on 
QDF2400 platform with mce-test without config migration enabled.

== dmesg ==
[   91.569358] Soft offlining page 0x1763c00 at 0x400000000000
[   91.569364] soft offline: 0x1763c00: migration failed 1, type 
100000000008008
[  150.282911] Soft offlining page 0x1763c00 at 0x400000000000
[  150.282917] soft offline: 0x1763c00: migration failed 1, type 
100000000008008

The mce-test failed as expected but did not encounter the soft lockups. 
(The test case might have an error it is missing an 'echo' in failure 
case.)

$ sudo ./run_hugepage_overcommit.sh

***************************************************************************
Pay attention:

This test checks that hugepage soft-offlining works under overcommitting.
***************************************************************************


-------------------------------------
TestCase ./thugetlb_overcommit 1
FAIL: migration failed.
Unpoisoning.

 	Num of Executed Test Case: 1	Num of Failed Case: 1

Tested-By: Manoj Iyer <manoj.iyer@canonical.com>

Thanks
Manoj Iyer

> [0] https://www.spinics.net/lists/arm-kernel/msg581657.html
> ---
> mm/migrate.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 89a0a1707f4c..187abd1526df 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1201,10 +1201,8 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
> 	 * tables or check whether the hugepage is pmd-based or not before
> 	 * kicking migration.
> 	 */
> -	if (!hugepage_migration_supported(page_hstate(hpage))) {
> -		putback_active_hugepage(hpage);
> +	if (!hugepage_migration_supported(page_hstate(hpage)))
> 		return -ENOSYS;
> -	}
>
> 	new_hpage = get_new_page(hpage, private, &result);
> 	if (!new_hpage)
>

--
============================
Manoj Iyer
Ubuntu/Canonical
ARM Servers - Cloud
============================

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
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Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Manoj Iyer]

On Wed, 24 May 2017, Punit Agrawal wrote:

> On failing to migrate a page, soft_offline_huge_page() performs the
> necessary update to the hugepage ref-count. When
> !hugepage_migration_supported() , unmap_and_move_hugepage() also
> decrements the page ref-count for the hugepage. The combined behaviour
> leaves the ref-count in an inconsistent state.
>
> This leads to soft lockups when running the overcommitted hugepage test
> from mce-tests suite.
>
> Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
> soft offline: 0x83ed600: migration failed 1, type
> 1fffc00000008008 (uptodate|head)
> INFO: rcu_preempt detected stalls on CPUs/tasks:
> Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
>  (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
>  thugetlb_overco R  running task        0  2715   2685 0x00000008
>  Call trace:
>  [<ffff000008089f90>] dump_backtrace+0x0/0x268
>  [<ffff00000808a2d4>] show_stack+0x24/0x30
>  [<ffff000008100d34>] sched_show_task+0x134/0x180
>  [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
>  [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
>  [<ffff000008143a3c>] update_process_times+0x34/0x60
>  [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
>  [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
>  [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
>  [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
>  [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
>  [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
>  [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
>  [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
>  [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0
>
> Fix this by dropping the ref-count decrement in
> unmap_and_move_hugepage() when !hugepage_migration_supported().
>
> Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
> Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
> Cc: Christoph Lameter <cl@linux.com>
> ---
> Hi Andrew,
>
> We ran into this bug when working towards enabling memory corruption
> on arm64. The patch was tested on an arm64 platform running v4.12-rc2
> with the series to enable memory corruption handling[0].
>
> Please consider merging as a fix for the 4.12 release.
>
> Thanks,
> Punit
>

I applied this patch applied to Ubuntu Zesty (4.10) kernel and tested on 
QDF2400 platform with mce-test without config migration enabled.

== dmesg ==
[   91.569358] Soft offlining page 0x1763c00 at 0x400000000000
[   91.569364] soft offline: 0x1763c00: migration failed 1, type 
100000000008008
[  150.282911] Soft offlining page 0x1763c00 at 0x400000000000
[  150.282917] soft offline: 0x1763c00: migration failed 1, type 
100000000008008

The mce-test failed as expected but did not encounter the soft lockups. 
(The test case might have an error it is missing an 'echo' in failure 
case.)

$ sudo ./run_hugepage_overcommit.sh

***************************************************************************
Pay attention:

This test checks that hugepage soft-offlining works under overcommitting.
***************************************************************************


-------------------------------------
TestCase ./thugetlb_overcommit 1
FAIL: migration failed.
Unpoisoning.

 	Num of Executed Test Case: 1	Num of Failed Case: 1

Tested-By: Manoj Iyer <manoj.iyer@canonical.com>

Thanks
Manoj Iyer

> [0] https://www.spinics.net/lists/arm-kernel/msg581657.html
> ---
> mm/migrate.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 89a0a1707f4c..187abd1526df 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1201,10 +1201,8 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
> 	 * tables or check whether the hugepage is pmd-based or not before
> 	 * kicking migration.
> 	 */
> -	if (!hugepage_migration_supported(page_hstate(hpage))) {
> -		putback_active_hugepage(hpage);
> +	if (!hugepage_migration_supported(page_hstate(hpage)))
> 		return -ENOSYS;
> -	}
>
> 	new_hpage = get_new_page(hpage, private, &result);
> 	if (!new_hpage)
>

--
============================
Manoj Iyer
Ubuntu/Canonical
ARM Servers - Cloud
============================

Re: [PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Naoya Horiguchi]

On Wed, May 24, 2017 at 04:47:28PM +0100, Punit Agrawal wrote:
> On failing to migrate a page, soft_offline_huge_page() performs the
> necessary update to the hugepage ref-count. When
> !hugepage_migration_supported() , unmap_and_move_hugepage() also
> decrements the page ref-count for the hugepage. The combined behaviour
> leaves the ref-count in an inconsistent state.
> 
> This leads to soft lockups when running the overcommitted hugepage test
> from mce-tests suite.
> 
> Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
> soft offline: 0x83ed600: migration failed 1, type
> 1fffc00000008008 (uptodate|head)
> INFO: rcu_preempt detected stalls on CPUs/tasks:
>  Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
>   (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
>   thugetlb_overco R  running task        0  2715   2685 0x00000008
>   Call trace:
>   [<ffff000008089f90>] dump_backtrace+0x0/0x268
>   [<ffff00000808a2d4>] show_stack+0x24/0x30
>   [<ffff000008100d34>] sched_show_task+0x134/0x180
>   [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
>   [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
>   [<ffff000008143a3c>] update_process_times+0x34/0x60
>   [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
>   [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
>   [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
>   [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
>   [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
>   [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
>   [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
>   [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
>   [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0
> 
> Fix this by dropping the ref-count decrement in
> unmap_and_move_hugepage() when !hugepage_migration_supported().
> 
> Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
> Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
> Cc: Christoph Lameter <cl@linux.com>
> 
> --
> Hi Andrew,
> 
> We ran into this bug when working towards enabling memory corruption
> on arm64. The patch was tested on an arm64 platform running v4.12-rc2
> with the series to enable memory corruption handling[0].
> 
> Please consider merging as a fix for the 4.12 release.
> 
> Thanks,
> Punit
> 
> [0] https://www.spinics.net/lists/arm-kernel/msg581657.html
> ---
>  mm/migrate.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 89a0a1707f4c..187abd1526df 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1201,10 +1201,8 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
>  	 * tables or check whether the hugepage is pmd-based or not before
>  	 * kicking migration.
>  	 */
> -	if (!hugepage_migration_supported(page_hstate(hpage))) {
> -		putback_active_hugepage(hpage);

Thank you for reporting and suggestion, Punit, Manoj.

Simply dropping this putback_active_hugepage() may resume the failure
counting issue addressed in 32665f2bbfed, so I would recommend to call
putback_movable_pages() in failure path in soft_offline_huge_page().

@@ -1600,7 +1600,8 @@ static int soft_offline_huge_page(struct page *page, int flags)
 		 * only one hugepage pointed to by hpage, so we need not
 		 * run through the pagelist here.
 		 */
-		putback_active_hugepage(hpage);
+		if (!list_empty(&pagelist))
+			putback_movable_pages(&pagelist);
 		if (ret > 0)
 			ret = -EIO;
 	} else {

Could you check this works for you?

Thanks,
Naoya Horiguchi

Re: [PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Naoya Horiguchi]

On Wed, May 24, 2017 at 04:47:28PM +0100, Punit Agrawal wrote:
> On failing to migrate a page, soft_offline_huge_page() performs the
> necessary update to the hugepage ref-count. When
> !hugepage_migration_supported() , unmap_and_move_hugepage() also
> decrements the page ref-count for the hugepage. The combined behaviour
> leaves the ref-count in an inconsistent state.
> 
> This leads to soft lockups when running the overcommitted hugepage test
> from mce-tests suite.
> 
> Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
> soft offline: 0x83ed600: migration failed 1, type
> 1fffc00000008008 (uptodate|head)
> INFO: rcu_preempt detected stalls on CPUs/tasks:
>  Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
>   (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
>   thugetlb_overco R  running task        0  2715   2685 0x00000008
>   Call trace:
>   [<ffff000008089f90>] dump_backtrace+0x0/0x268
>   [<ffff00000808a2d4>] show_stack+0x24/0x30
>   [<ffff000008100d34>] sched_show_task+0x134/0x180
>   [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
>   [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
>   [<ffff000008143a3c>] update_process_times+0x34/0x60
>   [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
>   [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
>   [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
>   [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
>   [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
>   [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
>   [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
>   [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
>   [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0
> 
> Fix this by dropping the ref-count decrement in
> unmap_and_move_hugepage() when !hugepage_migration_supported().
> 
> Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
> Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
> Cc: Christoph Lameter <cl@linux.com>
> 
> --
> Hi Andrew,
> 
> We ran into this bug when working towards enabling memory corruption
> on arm64. The patch was tested on an arm64 platform running v4.12-rc2
> with the series to enable memory corruption handling[0].
> 
> Please consider merging as a fix for the 4.12 release.
> 
> Thanks,
> Punit
> 
> [0] https://www.spinics.net/lists/arm-kernel/msg581657.html
> ---
>  mm/migrate.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 89a0a1707f4c..187abd1526df 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1201,10 +1201,8 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
>  	 * tables or check whether the hugepage is pmd-based or not before
>  	 * kicking migration.
>  	 */
> -	if (!hugepage_migration_supported(page_hstate(hpage))) {
> -		putback_active_hugepage(hpage);

Thank you for reporting and suggestion, Punit, Manoj.

Simply dropping this putback_active_hugepage() may resume the failure
counting issue addressed in 32665f2bbfed, so I would recommend to call
putback_movable_pages() in failure path in soft_offline_huge_page().

@@ -1600,7 +1600,8 @@ static int soft_offline_huge_page(struct page *page, int flags)
 		 * only one hugepage pointed to by hpage, so we need not
 		 * run through the pagelist here.
 		 */
-		putback_active_hugepage(hpage);
+		if (!list_empty(&pagelist))
+			putback_movable_pages(&pagelist);
 		if (ret > 0)
 			ret = -EIO;
 	} else {

Could you check this works for you?

Thanks,
Naoya Horiguchi
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
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[PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Naoya Horiguchi]

On Wed, May 24, 2017 at 04:47:28PM +0100, Punit Agrawal wrote:
> On failing to migrate a page, soft_offline_huge_page() performs the
> necessary update to the hugepage ref-count. When
> !hugepage_migration_supported() , unmap_and_move_hugepage() also
> decrements the page ref-count for the hugepage. The combined behaviour
> leaves the ref-count in an inconsistent state.
> 
> This leads to soft lockups when running the overcommitted hugepage test
> from mce-tests suite.
> 
> Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
> soft offline: 0x83ed600: migration failed 1, type
> 1fffc00000008008 (uptodate|head)
> INFO: rcu_preempt detected stalls on CPUs/tasks:
>  Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
>   (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
>   thugetlb_overco R  running task        0  2715   2685 0x00000008
>   Call trace:
>   [<ffff000008089f90>] dump_backtrace+0x0/0x268
>   [<ffff00000808a2d4>] show_stack+0x24/0x30
>   [<ffff000008100d34>] sched_show_task+0x134/0x180
>   [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
>   [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
>   [<ffff000008143a3c>] update_process_times+0x34/0x60
>   [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
>   [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
>   [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
>   [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
>   [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
>   [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
>   [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
>   [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
>   [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0
> 
> Fix this by dropping the ref-count decrement in
> unmap_and_move_hugepage() when !hugepage_migration_supported().
> 
> Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
> Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
> Cc: Christoph Lameter <cl@linux.com>
> 
> --
> Hi Andrew,
> 
> We ran into this bug when working towards enabling memory corruption
> on arm64. The patch was tested on an arm64 platform running v4.12-rc2
> with the series to enable memory corruption handling[0].
> 
> Please consider merging as a fix for the 4.12 release.
> 
> Thanks,
> Punit
> 
> [0] https://www.spinics.net/lists/arm-kernel/msg581657.html
> ---
>  mm/migrate.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 89a0a1707f4c..187abd1526df 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -1201,10 +1201,8 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
>  	 * tables or check whether the hugepage is pmd-based or not before
>  	 * kicking migration.
>  	 */
> -	if (!hugepage_migration_supported(page_hstate(hpage))) {
> -		putback_active_hugepage(hpage);

Thank you for reporting and suggestion, Punit, Manoj.

Simply dropping this putback_active_hugepage() may resume the failure
counting issue addressed in 32665f2bbfed, so I would recommend to call
putback_movable_pages() in failure path in soft_offline_huge_page().

@@ -1600,7 +1600,8 @@ static int soft_offline_huge_page(struct page *page, int flags)
 		 * only one hugepage pointed to by hpage, so we need not
 		 * run through the pagelist here.
 		 */
-		putback_active_hugepage(hpage);
+		if (!list_empty(&pagelist))
+			putback_movable_pages(&pagelist);
 		if (ret > 0)
 			ret = -EIO;
 	} else {

Could you check this works for you?

Thanks,
Naoya Horiguchi

Re: [PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Naoya Horiguchi]

On Wed, May 24, 2017 at 12:56:10PM -0700, Andrew Morton wrote:
> On Wed, 24 May 2017 16:47:28 +0100 Punit Agrawal <punit.agrawal@arm.com> wrote:
> 
> > On failing to migrate a page, soft_offline_huge_page() performs the
> > necessary update to the hugepage ref-count. When
> > !hugepage_migration_supported() , unmap_and_move_hugepage() also
> > decrements the page ref-count for the hugepage. The combined behaviour
> > leaves the ref-count in an inconsistent state.
> > 
> > This leads to soft lockups when running the overcommitted hugepage test
> > from mce-tests suite.
> > 
> > Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
> > soft offline: 0x83ed600: migration failed 1, type
> > 1fffc00000008008 (uptodate|head)
> > INFO: rcu_preempt detected stalls on CPUs/tasks:
> >  Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
> >   (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
> >   thugetlb_overco R  running task        0  2715   2685 0x00000008
> >   Call trace:
> >   [<ffff000008089f90>] dump_backtrace+0x0/0x268
> >   [<ffff00000808a2d4>] show_stack+0x24/0x30
> >   [<ffff000008100d34>] sched_show_task+0x134/0x180
> >   [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
> >   [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
> >   [<ffff000008143a3c>] update_process_times+0x34/0x60
> >   [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
> >   [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
> >   [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
> >   [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
> >   [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
> >   [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
> >   [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
> >   [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
> >   [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0
> > 
> > Fix this by dropping the ref-count decrement in
> > unmap_and_move_hugepage() when !hugepage_migration_supported().
> > 
> > Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
> > Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
> > Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> > Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> > Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> > Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
> > Cc: Christoph Lameter <cl@linux.com>
> 
> 32665f2bbfed was three years ago.  Do you have any theory as to why
> this took so long to be detected?

My per-release testing only ran for "hugepage_migration_supported() == true"
setting (i.e. x86 with CONFIG_HUGETLB_PAGE=y). I need extend the coverage.
And other arch's developers recently have come to have interest in hugepage
migration.

>  And do you believe a -stable
> backport is warranted?

I agree to send the fix to stable, so the stable tag is wanted.

Cc: stable@kernel.org   # v3.14+

Thanks,
Naoya Horiguchi

Re: [PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Naoya Horiguchi]

On Wed, May 24, 2017 at 12:56:10PM -0700, Andrew Morton wrote:
> On Wed, 24 May 2017 16:47:28 +0100 Punit Agrawal <punit.agrawal@arm.com> wrote:
> 
> > On failing to migrate a page, soft_offline_huge_page() performs the
> > necessary update to the hugepage ref-count. When
> > !hugepage_migration_supported() , unmap_and_move_hugepage() also
> > decrements the page ref-count for the hugepage. The combined behaviour
> > leaves the ref-count in an inconsistent state.
> > 
> > This leads to soft lockups when running the overcommitted hugepage test
> > from mce-tests suite.
> > 
> > Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
> > soft offline: 0x83ed600: migration failed 1, type
> > 1fffc00000008008 (uptodate|head)
> > INFO: rcu_preempt detected stalls on CPUs/tasks:
> >  Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
> >   (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
> >   thugetlb_overco R  running task        0  2715   2685 0x00000008
> >   Call trace:
> >   [<ffff000008089f90>] dump_backtrace+0x0/0x268
> >   [<ffff00000808a2d4>] show_stack+0x24/0x30
> >   [<ffff000008100d34>] sched_show_task+0x134/0x180
> >   [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
> >   [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
> >   [<ffff000008143a3c>] update_process_times+0x34/0x60
> >   [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
> >   [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
> >   [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
> >   [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
> >   [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
> >   [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
> >   [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
> >   [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
> >   [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0
> > 
> > Fix this by dropping the ref-count decrement in
> > unmap_and_move_hugepage() when !hugepage_migration_supported().
> > 
> > Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
> > Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
> > Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> > Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> > Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> > Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
> > Cc: Christoph Lameter <cl@linux.com>
> 
> 32665f2bbfed was three years ago.  Do you have any theory as to why
> this took so long to be detected?

My per-release testing only ran for "hugepage_migration_supported() == true"
setting (i.e. x86 with CONFIG_HUGETLB_PAGE=y). I need extend the coverage.
And other arch's developers recently have come to have interest in hugepage
migration.

>  And do you believe a -stable
> backport is warranted?

I agree to send the fix to stable, so the stable tag is wanted.

Cc: stable@kernel.org   # v3.14+

Thanks,
Naoya Horiguchi
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To unsubscribe, send a message with 'unsubscribe linux-mm' in
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[PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Naoya Horiguchi]

On Wed, May 24, 2017 at 12:56:10PM -0700, Andrew Morton wrote:
> On Wed, 24 May 2017 16:47:28 +0100 Punit Agrawal <punit.agrawal@arm.com> wrote:
> 
> > On failing to migrate a page, soft_offline_huge_page() performs the
> > necessary update to the hugepage ref-count. When
> > !hugepage_migration_supported() , unmap_and_move_hugepage() also
> > decrements the page ref-count for the hugepage. The combined behaviour
> > leaves the ref-count in an inconsistent state.
> > 
> > This leads to soft lockups when running the overcommitted hugepage test
> > from mce-tests suite.
> > 
> > Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
> > soft offline: 0x83ed600: migration failed 1, type
> > 1fffc00000008008 (uptodate|head)
> > INFO: rcu_preempt detected stalls on CPUs/tasks:
> >  Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
> >   (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
> >   thugetlb_overco R  running task        0  2715   2685 0x00000008
> >   Call trace:
> >   [<ffff000008089f90>] dump_backtrace+0x0/0x268
> >   [<ffff00000808a2d4>] show_stack+0x24/0x30
> >   [<ffff000008100d34>] sched_show_task+0x134/0x180
> >   [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
> >   [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
> >   [<ffff000008143a3c>] update_process_times+0x34/0x60
> >   [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
> >   [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
> >   [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
> >   [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
> >   [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
> >   [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
> >   [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
> >   [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
> >   [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0
> > 
> > Fix this by dropping the ref-count decrement in
> > unmap_and_move_hugepage() when !hugepage_migration_supported().
> > 
> > Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
> > Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
> > Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
> > Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> > Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
> > Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
> > Cc: Christoph Lameter <cl@linux.com>
> 
> 32665f2bbfed was three years ago.  Do you have any theory as to why
> this took so long to be detected?

My per-release testing only ran for "hugepage_migration_supported() == true"
setting (i.e. x86 with CONFIG_HUGETLB_PAGE=y). I need extend the coverage.
And other arch's developers recently have come to have interest in hugepage
migration.

>  And do you believe a -stable
> backport is warranted?

I agree to send the fix to stable, so the stable tag is wanted.

Cc: stable at kernel.org   # v3.14+

Thanks,
Naoya Horiguchi

Re: [PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Punit Agrawal]

Andrew Morton <akpm@linux-foundation.org> writes:

> On Wed, 24 May 2017 16:47:28 +0100 Punit Agrawal <punit.agrawal@arm.com> wrote:
>
>> On failing to migrate a page, soft_offline_huge_page() performs the
>> necessary update to the hugepage ref-count. When
>> !hugepage_migration_supported() , unmap_and_move_hugepage() also
>> decrements the page ref-count for the hugepage. The combined behaviour
>> leaves the ref-count in an inconsistent state.
>> 
>> This leads to soft lockups when running the overcommitted hugepage test
>> from mce-tests suite.
>> 
>> Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
>> soft offline: 0x83ed600: migration failed 1, type
>> 1fffc00000008008 (uptodate|head)
>> INFO: rcu_preempt detected stalls on CPUs/tasks:
>>  Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
>>   (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
>>   thugetlb_overco R  running task        0  2715   2685 0x00000008
>>   Call trace:
>>   [<ffff000008089f90>] dump_backtrace+0x0/0x268
>>   [<ffff00000808a2d4>] show_stack+0x24/0x30
>>   [<ffff000008100d34>] sched_show_task+0x134/0x180
>>   [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
>>   [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
>>   [<ffff000008143a3c>] update_process_times+0x34/0x60
>>   [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
>>   [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
>>   [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
>>   [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
>>   [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
>>   [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
>>   [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
>>   [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
>>   [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0
>> 
>> Fix this by dropping the ref-count decrement in
>> unmap_and_move_hugepage() when !hugepage_migration_supported().
>> 
>> Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
>> Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
>> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
>> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
>> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
>> Cc: Christoph Lameter <cl@linux.com>
>
> 32665f2bbfed was three years ago.  Do you have any theory as to why
> this took so long to be detected?

This only triggers on systems that enable memory failure handling
(ARCH_SUPPORTS_MEMORY_FAILURE) but not hugepage migration
(!ARCH_ENABLE_HUGEPAGE_MIGRATION).

I imagine this wasn't triggered as there aren't many systems running
this configuration.

> And do you believe a -stable backport is warranted?

I'll defer to Horiguchi-san's judgement here.

>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Punit Agrawal]

Andrew Morton <akpm@linux-foundation.org> writes:

> On Wed, 24 May 2017 16:47:28 +0100 Punit Agrawal <punit.agrawal@arm.com> wrote:
>
>> On failing to migrate a page, soft_offline_huge_page() performs the
>> necessary update to the hugepage ref-count. When
>> !hugepage_migration_supported() , unmap_and_move_hugepage() also
>> decrements the page ref-count for the hugepage. The combined behaviour
>> leaves the ref-count in an inconsistent state.
>> 
>> This leads to soft lockups when running the overcommitted hugepage test
>> from mce-tests suite.
>> 
>> Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
>> soft offline: 0x83ed600: migration failed 1, type
>> 1fffc00000008008 (uptodate|head)
>> INFO: rcu_preempt detected stalls on CPUs/tasks:
>>  Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
>>   (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
>>   thugetlb_overco R  running task        0  2715   2685 0x00000008
>>   Call trace:
>>   [<ffff000008089f90>] dump_backtrace+0x0/0x268
>>   [<ffff00000808a2d4>] show_stack+0x24/0x30
>>   [<ffff000008100d34>] sched_show_task+0x134/0x180
>>   [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
>>   [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
>>   [<ffff000008143a3c>] update_process_times+0x34/0x60
>>   [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
>>   [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
>>   [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
>>   [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
>>   [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
>>   [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
>>   [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
>>   [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
>>   [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0
>> 
>> Fix this by dropping the ref-count decrement in
>> unmap_and_move_hugepage() when !hugepage_migration_supported().
>> 
>> Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
>> Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
>> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
>> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
>> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
>> Cc: Christoph Lameter <cl@linux.com>
>
> 32665f2bbfed was three years ago.  Do you have any theory as to why
> this took so long to be detected?

This only triggers on systems that enable memory failure handling
(ARCH_SUPPORTS_MEMORY_FAILURE) but not hugepage migration
(!ARCH_ENABLE_HUGEPAGE_MIGRATION).

I imagine this wasn't triggered as there aren't many systems running
this configuration.

> And do you believe a -stable backport is warranted?

I'll defer to Horiguchi-san's judgement here.

>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

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To unsubscribe, send a message with 'unsubscribe linux-mm' in
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[PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Punit Agrawal]

Andrew Morton <akpm@linux-foundation.org> writes:

> On Wed, 24 May 2017 16:47:28 +0100 Punit Agrawal <punit.agrawal@arm.com> wrote:
>
>> On failing to migrate a page, soft_offline_huge_page() performs the
>> necessary update to the hugepage ref-count. When
>> !hugepage_migration_supported() , unmap_and_move_hugepage() also
>> decrements the page ref-count for the hugepage. The combined behaviour
>> leaves the ref-count in an inconsistent state.
>> 
>> This leads to soft lockups when running the overcommitted hugepage test
>> from mce-tests suite.
>> 
>> Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
>> soft offline: 0x83ed600: migration failed 1, type
>> 1fffc00000008008 (uptodate|head)
>> INFO: rcu_preempt detected stalls on CPUs/tasks:
>>  Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
>>   (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
>>   thugetlb_overco R  running task        0  2715   2685 0x00000008
>>   Call trace:
>>   [<ffff000008089f90>] dump_backtrace+0x0/0x268
>>   [<ffff00000808a2d4>] show_stack+0x24/0x30
>>   [<ffff000008100d34>] sched_show_task+0x134/0x180
>>   [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
>>   [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
>>   [<ffff000008143a3c>] update_process_times+0x34/0x60
>>   [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
>>   [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
>>   [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
>>   [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
>>   [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
>>   [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
>>   [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
>>   [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
>>   [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0
>> 
>> Fix this by dropping the ref-count decrement in
>> unmap_and_move_hugepage() when !hugepage_migration_supported().
>> 
>> Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
>> Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
>> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
>> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
>> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
>> Cc: Christoph Lameter <cl@linux.com>
>
> 32665f2bbfed was three years ago.  Do you have any theory as to why
> this took so long to be detected?

This only triggers on systems that enable memory failure handling
(ARCH_SUPPORTS_MEMORY_FAILURE) but not hugepage migration
(!ARCH_ENABLE_HUGEPAGE_MIGRATION).

I imagine this wasn't triggered as there aren't many systems running
this configuration.

> And do you believe a -stable backport is warranted?

I'll defer to Horiguchi-san's judgement here.

>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo at kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email at kvack.org </a>

Re: [PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Punit Agrawal]

Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> writes:

> On Wed, May 24, 2017 at 04:47:28PM +0100, Punit Agrawal wrote:
>> On failing to migrate a page, soft_offline_huge_page() performs the
>> necessary update to the hugepage ref-count. When
>> !hugepage_migration_supported() , unmap_and_move_hugepage() also
>> decrements the page ref-count for the hugepage. The combined behaviour
>> leaves the ref-count in an inconsistent state.
>> 
>> This leads to soft lockups when running the overcommitted hugepage test
>> from mce-tests suite.
>> 
>> Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
>> soft offline: 0x83ed600: migration failed 1, type
>> 1fffc00000008008 (uptodate|head)
>> INFO: rcu_preempt detected stalls on CPUs/tasks:
>>  Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
>>   (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
>>   thugetlb_overco R  running task        0  2715   2685 0x00000008
>>   Call trace:
>>   [<ffff000008089f90>] dump_backtrace+0x0/0x268
>>   [<ffff00000808a2d4>] show_stack+0x24/0x30
>>   [<ffff000008100d34>] sched_show_task+0x134/0x180
>>   [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
>>   [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
>>   [<ffff000008143a3c>] update_process_times+0x34/0x60
>>   [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
>>   [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
>>   [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
>>   [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
>>   [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
>>   [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
>>   [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
>>   [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
>>   [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0
>> 
>> Fix this by dropping the ref-count decrement in
>> unmap_and_move_hugepage() when !hugepage_migration_supported().
>> 
>> Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
>> Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
>> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
>> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
>> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
>> Cc: Christoph Lameter <cl@linux.com>
>> 
>> --
>> Hi Andrew,
>> 
>> We ran into this bug when working towards enabling memory corruption
>> on arm64. The patch was tested on an arm64 platform running v4.12-rc2
>> with the series to enable memory corruption handling[0].
>> 
>> Please consider merging as a fix for the 4.12 release.
>> 
>> Thanks,
>> Punit
>> 
>> [0] https://www.spinics.net/lists/arm-kernel/msg581657.html
>> ---
>>  mm/migrate.c | 4 +---
>>  1 file changed, 1 insertion(+), 3 deletions(-)
>> 
>> diff --git a/mm/migrate.c b/mm/migrate.c
>> index 89a0a1707f4c..187abd1526df 100644
>> --- a/mm/migrate.c
>> +++ b/mm/migrate.c
>> @@ -1201,10 +1201,8 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
>>  	 * tables or check whether the hugepage is pmd-based or not before
>>  	 * kicking migration.
>>  	 */
>> -	if (!hugepage_migration_supported(page_hstate(hpage))) {
>> -		putback_active_hugepage(hpage);
>
> Thank you for reporting and suggestion, Punit, Manoj.
>
> Simply dropping this putback_active_hugepage() may resume the failure
> counting issue addressed in 32665f2bbfed, so I would recommend to call
> putback_movable_pages() in failure path in soft_offline_huge_page().
>
> @@ -1600,7 +1600,8 @@ static int soft_offline_huge_page(struct page *page, int flags)
>  		 * only one hugepage pointed to by hpage, so we need not
>  		 * run through the pagelist here.
>  		 */
> -		putback_active_hugepage(hpage);
> +		if (!list_empty(&pagelist))
> +			putback_movable_pages(&pagelist);
>  		if (ret > 0)
>  			ret = -EIO;
>  	} else {
>
> Could you check this works for you?

Using this sequence works as well. I'll send out an update shortly.

Thanks

>
> Thanks,
> Naoya Horiguchi
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

Re: [PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Punit Agrawal]

Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> writes:

> On Wed, May 24, 2017 at 04:47:28PM +0100, Punit Agrawal wrote:
>> On failing to migrate a page, soft_offline_huge_page() performs the
>> necessary update to the hugepage ref-count. When
>> !hugepage_migration_supported() , unmap_and_move_hugepage() also
>> decrements the page ref-count for the hugepage. The combined behaviour
>> leaves the ref-count in an inconsistent state.
>> 
>> This leads to soft lockups when running the overcommitted hugepage test
>> from mce-tests suite.
>> 
>> Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
>> soft offline: 0x83ed600: migration failed 1, type
>> 1fffc00000008008 (uptodate|head)
>> INFO: rcu_preempt detected stalls on CPUs/tasks:
>>  Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
>>   (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
>>   thugetlb_overco R  running task        0  2715   2685 0x00000008
>>   Call trace:
>>   [<ffff000008089f90>] dump_backtrace+0x0/0x268
>>   [<ffff00000808a2d4>] show_stack+0x24/0x30
>>   [<ffff000008100d34>] sched_show_task+0x134/0x180
>>   [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
>>   [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
>>   [<ffff000008143a3c>] update_process_times+0x34/0x60
>>   [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
>>   [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
>>   [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
>>   [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
>>   [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
>>   [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
>>   [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
>>   [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
>>   [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0
>> 
>> Fix this by dropping the ref-count decrement in
>> unmap_and_move_hugepage() when !hugepage_migration_supported().
>> 
>> Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
>> Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
>> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
>> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
>> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
>> Cc: Christoph Lameter <cl@linux.com>
>> 
>> --
>> Hi Andrew,
>> 
>> We ran into this bug when working towards enabling memory corruption
>> on arm64. The patch was tested on an arm64 platform running v4.12-rc2
>> with the series to enable memory corruption handling[0].
>> 
>> Please consider merging as a fix for the 4.12 release.
>> 
>> Thanks,
>> Punit
>> 
>> [0] https://www.spinics.net/lists/arm-kernel/msg581657.html
>> ---
>>  mm/migrate.c | 4 +---
>>  1 file changed, 1 insertion(+), 3 deletions(-)
>> 
>> diff --git a/mm/migrate.c b/mm/migrate.c
>> index 89a0a1707f4c..187abd1526df 100644
>> --- a/mm/migrate.c
>> +++ b/mm/migrate.c
>> @@ -1201,10 +1201,8 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
>>  	 * tables or check whether the hugepage is pmd-based or not before
>>  	 * kicking migration.
>>  	 */
>> -	if (!hugepage_migration_supported(page_hstate(hpage))) {
>> -		putback_active_hugepage(hpage);
>
> Thank you for reporting and suggestion, Punit, Manoj.
>
> Simply dropping this putback_active_hugepage() may resume the failure
> counting issue addressed in 32665f2bbfed, so I would recommend to call
> putback_movable_pages() in failure path in soft_offline_huge_page().
>
> @@ -1600,7 +1600,8 @@ static int soft_offline_huge_page(struct page *page, int flags)
>  		 * only one hugepage pointed to by hpage, so we need not
>  		 * run through the pagelist here.
>  		 */
> -		putback_active_hugepage(hpage);
> +		if (!list_empty(&pagelist))
> +			putback_movable_pages(&pagelist);
>  		if (ret > 0)
>  			ret = -EIO;
>  	} else {
>
> Could you check this works for you?

Using this sequence works as well. I'll send out an update shortly.

Thanks

>
> Thanks,
> Naoya Horiguchi
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

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To unsubscribe, send a message with 'unsubscribe linux-mm' in
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Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>

[PATCH] mm/migrate: Fix ref-count handling when !hugepage_migration_supported()

[Punit Agrawal]

Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> writes:

> On Wed, May 24, 2017 at 04:47:28PM +0100, Punit Agrawal wrote:
>> On failing to migrate a page, soft_offline_huge_page() performs the
>> necessary update to the hugepage ref-count. When
>> !hugepage_migration_supported() , unmap_and_move_hugepage() also
>> decrements the page ref-count for the hugepage. The combined behaviour
>> leaves the ref-count in an inconsistent state.
>> 
>> This leads to soft lockups when running the overcommitted hugepage test
>> from mce-tests suite.
>> 
>> Soft offlining pfn 0x83ed600 at process virtual address 0x400000000000
>> soft offline: 0x83ed600: migration failed 1, type
>> 1fffc00000008008 (uptodate|head)
>> INFO: rcu_preempt detected stalls on CPUs/tasks:
>>  Tasks blocked on level-0 rcu_node (CPUs 0-7): P2715
>>   (detected by 7, t=5254 jiffies, g=963, c=962, q=321)
>>   thugetlb_overco R  running task        0  2715   2685 0x00000008
>>   Call trace:
>>   [<ffff000008089f90>] dump_backtrace+0x0/0x268
>>   [<ffff00000808a2d4>] show_stack+0x24/0x30
>>   [<ffff000008100d34>] sched_show_task+0x134/0x180
>>   [<ffff0000081c90fc>] rcu_print_detail_task_stall_rnp+0x54/0x7c
>>   [<ffff00000813cfd4>] rcu_check_callbacks+0xa74/0xb08
>>   [<ffff000008143a3c>] update_process_times+0x34/0x60
>>   [<ffff0000081550e8>] tick_sched_handle.isra.7+0x38/0x70
>>   [<ffff00000815516c>] tick_sched_timer+0x4c/0x98
>>   [<ffff0000081442e0>] __hrtimer_run_queues+0xc0/0x300
>>   [<ffff000008144fa4>] hrtimer_interrupt+0xac/0x228
>>   [<ffff0000089a56d4>] arch_timer_handler_phys+0x3c/0x50
>>   [<ffff00000812f1bc>] handle_percpu_devid_irq+0x8c/0x290
>>   [<ffff0000081297fc>] generic_handle_irq+0x34/0x50
>>   [<ffff000008129f00>] __handle_domain_irq+0x68/0xc0
>>   [<ffff0000080816b4>] gic_handle_irq+0x5c/0xb0
>> 
>> Fix this by dropping the ref-count decrement in
>> unmap_and_move_hugepage() when !hugepage_migration_supported().
>> 
>> Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
>> Reported-by: Manoj Iyer <manoj.iyer@canonical.com>
>> Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
>> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
>> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com>
>> Cc: Christoph Lameter <cl@linux.com>
>> 
>> --
>> Hi Andrew,
>> 
>> We ran into this bug when working towards enabling memory corruption
>> on arm64. The patch was tested on an arm64 platform running v4.12-rc2
>> with the series to enable memory corruption handling[0].
>> 
>> Please consider merging as a fix for the 4.12 release.
>> 
>> Thanks,
>> Punit
>> 
>> [0] https://www.spinics.net/lists/arm-kernel/msg581657.html
>> ---
>>  mm/migrate.c | 4 +---
>>  1 file changed, 1 insertion(+), 3 deletions(-)
>> 
>> diff --git a/mm/migrate.c b/mm/migrate.c
>> index 89a0a1707f4c..187abd1526df 100644
>> --- a/mm/migrate.c
>> +++ b/mm/migrate.c
>> @@ -1201,10 +1201,8 @@ static int unmap_and_move_huge_page(new_page_t get_new_page,
>>  	 * tables or check whether the hugepage is pmd-based or not before
>>  	 * kicking migration.
>>  	 */
>> -	if (!hugepage_migration_supported(page_hstate(hpage))) {
>> -		putback_active_hugepage(hpage);
>
> Thank you for reporting and suggestion, Punit, Manoj.
>
> Simply dropping this putback_active_hugepage() may resume the failure
> counting issue addressed in 32665f2bbfed, so I would recommend to call
> putback_movable_pages() in failure path in soft_offline_huge_page().
>
> @@ -1600,7 +1600,8 @@ static int soft_offline_huge_page(struct page *page, int flags)
>  		 * only one hugepage pointed to by hpage, so we need not
>  		 * run through the pagelist here.
>  		 */
> -		putback_active_hugepage(hpage);
> +		if (!list_empty(&pagelist))
> +			putback_movable_pages(&pagelist);
>  		if (ret > 0)
>  			ret = -EIO;
>  	} else {
>
> Could you check this works for you?

Using this sequence works as well. I'll send out an update shortly.

Thanks

>
> Thanks,
> Naoya Horiguchi
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo at kvack.org.  For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email at kvack.org </a>