* [PATCH v2 0/8] A few cleanup and fixup patches for memory failure
@ 2022-02-16 9:14 Miaohe Lin
2022-02-16 9:14 ` [PATCH v2 1/8] mm/memory-failure.c: minor clean up for memory_failure_dev_pagemap Miaohe Lin
` (7 more replies)
0 siblings, 8 replies; 11+ messages in thread
From: Miaohe Lin @ 2022-02-16 9:14 UTC (permalink / raw)
To: akpm, naoya.horiguchi; +Cc: linux-mm, linux-kernel, linmiaohe
Hi,
This series contains a few patches to simplify the code logic, remove
unneeded variable and remove obsolete comment. Also we fix race changing
page more robustly in memory_failure. More details can be found in the
respective changelogs. Thanks!
---
v1->v2:
Collect Acked-by tag and fix review comment.
Thanks Naoya.
---
Miaohe Lin (8):
mm/memory-failure.c: minor clean up for memory_failure_dev_pagemap
mm/memory-failure.c: catch unexpected -EFAULT from vma_address()
mm/memory-failure.c: rework the signaling logic in kill_proc
mm/memory-failure.c: fix race with changing page more robustly
mm/memory-failure.c: remove PageSlab check in hwpoison_filter_dev
mm/memory-failure.c: rework the try_to_unmap logic in
hwpoison_user_mappings()
mm/memory-failure.c: remove obsolete comment in __soft_offline_page
mm/memory-failure.c: remove unnecessary PageTransTail check
mm/memory-failure.c | 87 +++++++++++++++++++--------------------------
1 file changed, 37 insertions(+), 50 deletions(-)
--
2.23.0
^ permalink raw reply [flat|nested] 11+ messages in thread
* [PATCH v2 1/8] mm/memory-failure.c: minor clean up for memory_failure_dev_pagemap
2022-02-16 9:14 [PATCH v2 0/8] A few cleanup and fixup patches for memory failure Miaohe Lin
@ 2022-02-16 9:14 ` Miaohe Lin
2022-02-16 9:14 ` [PATCH v2 2/8] mm/memory-failure.c: catch unexpected -EFAULT from vma_address() Miaohe Lin
` (6 subsequent siblings)
7 siblings, 0 replies; 11+ messages in thread
From: Miaohe Lin @ 2022-02-16 9:14 UTC (permalink / raw)
To: akpm, naoya.horiguchi; +Cc: linux-mm, linux-kernel, linmiaohe
The flags always has MF_ACTION_REQUIRED and MF_MUST_KILL set. So we do
not need to check these flags again.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
---
mm/memory-failure.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 55edb0cc3848..b3ff7e99a421 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1644,7 +1644,7 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
* SIGBUS (i.e. MF_MUST_KILL)
*/
flags |= MF_ACTION_REQUIRED | MF_MUST_KILL;
- collect_procs(page, &tokill, flags & MF_ACTION_REQUIRED);
+ collect_procs(page, &tokill, true);
list_for_each_entry(tk, &tokill, nd)
if (tk->size_shift)
@@ -1659,7 +1659,7 @@ static int memory_failure_dev_pagemap(unsigned long pfn, int flags,
start = (page->index << PAGE_SHIFT) & ~(size - 1);
unmap_mapping_range(page->mapping, start, size, 0);
}
- kill_procs(&tokill, flags & MF_MUST_KILL, false, pfn, flags);
+ kill_procs(&tokill, true, false, pfn, flags);
rc = 0;
unlock:
dax_unlock_page(page, cookie);
--
2.23.0
^ permalink raw reply related [flat|nested] 11+ messages in thread
* [PATCH v2 2/8] mm/memory-failure.c: catch unexpected -EFAULT from vma_address()
2022-02-16 9:14 [PATCH v2 0/8] A few cleanup and fixup patches for memory failure Miaohe Lin
2022-02-16 9:14 ` [PATCH v2 1/8] mm/memory-failure.c: minor clean up for memory_failure_dev_pagemap Miaohe Lin
@ 2022-02-16 9:14 ` Miaohe Lin
2022-02-16 9:14 ` [PATCH v2 3/8] mm/memory-failure.c: rework the signaling logic in kill_proc Miaohe Lin
` (5 subsequent siblings)
7 siblings, 0 replies; 11+ messages in thread
From: Miaohe Lin @ 2022-02-16 9:14 UTC (permalink / raw)
To: akpm, naoya.horiguchi; +Cc: linux-mm, linux-kernel, linmiaohe
It's unexpected to walk the page table when vma_address() return -EFAULT.
But dev_pagemap_mapping_shift() is called only when vma associated to the
error page is found already in collect_procs_{file,anon}, so vma_address()
should not return -EFAULT except with some bug, as Naoya pointed out. We
can use VM_BUG_ON_VMA() to catch this bug here.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
---
mm/memory-failure.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index b3ff7e99a421..eaa241058401 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -315,6 +315,7 @@ static unsigned long dev_pagemap_mapping_shift(struct page *page,
pmd_t *pmd;
pte_t *pte;
+ VM_BUG_ON_VMA(address == -EFAULT, vma);
pgd = pgd_offset(vma->vm_mm, address);
if (!pgd_present(*pgd))
return 0;
--
2.23.0
^ permalink raw reply related [flat|nested] 11+ messages in thread
* [PATCH v2 3/8] mm/memory-failure.c: rework the signaling logic in kill_proc
2022-02-16 9:14 [PATCH v2 0/8] A few cleanup and fixup patches for memory failure Miaohe Lin
2022-02-16 9:14 ` [PATCH v2 1/8] mm/memory-failure.c: minor clean up for memory_failure_dev_pagemap Miaohe Lin
2022-02-16 9:14 ` [PATCH v2 2/8] mm/memory-failure.c: catch unexpected -EFAULT from vma_address() Miaohe Lin
@ 2022-02-16 9:14 ` Miaohe Lin
2022-02-16 9:14 ` [PATCH v2 4/8] mm/memory-failure.c: fix race with changing page more robustly Miaohe Lin
` (4 subsequent siblings)
7 siblings, 0 replies; 11+ messages in thread
From: Miaohe Lin @ 2022-02-16 9:14 UTC (permalink / raw)
To: akpm, naoya.horiguchi; +Cc: linux-mm, linux-kernel, linmiaohe
BUS_MCEERR_AR code is only sent when MF_ACTION_REQUIRED is set and the
target is current. Rework the code to make this clear.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
---
mm/memory-failure.c | 16 ++++++----------
1 file changed, 6 insertions(+), 10 deletions(-)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index eaa241058401..7e205d91b2d7 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -258,16 +258,13 @@ static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)
pr_err("Memory failure: %#lx: Sending SIGBUS to %s:%d due to hardware memory corruption\n",
pfn, t->comm, t->pid);
- if (flags & MF_ACTION_REQUIRED) {
- if (t == current)
- ret = force_sig_mceerr(BUS_MCEERR_AR,
- (void __user *)tk->addr, addr_lsb);
- else
- /* Signal other processes sharing the page if they have PF_MCE_EARLY set. */
- ret = send_sig_mceerr(BUS_MCEERR_AO, (void __user *)tk->addr,
- addr_lsb, t);
- } else {
+ if ((flags & MF_ACTION_REQUIRED) && (t == current))
+ ret = force_sig_mceerr(BUS_MCEERR_AR,
+ (void __user *)tk->addr, addr_lsb);
+ else
/*
+ * Signal other processes sharing the page if they have
+ * PF_MCE_EARLY set.
* Don't use force here, it's convenient if the signal
* can be temporarily blocked.
* This could cause a loop when the user sets SIGBUS
@@ -275,7 +272,6 @@ static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags)
*/
ret = send_sig_mceerr(BUS_MCEERR_AO, (void __user *)tk->addr,
addr_lsb, t); /* synchronous? */
- }
if (ret < 0)
pr_info("Memory failure: Error sending signal to %s:%d: %d\n",
t->comm, t->pid, ret);
--
2.23.0
^ permalink raw reply related [flat|nested] 11+ messages in thread
* [PATCH v2 4/8] mm/memory-failure.c: fix race with changing page more robustly
2022-02-16 9:14 [PATCH v2 0/8] A few cleanup and fixup patches for memory failure Miaohe Lin
` (2 preceding siblings ...)
2022-02-16 9:14 ` [PATCH v2 3/8] mm/memory-failure.c: rework the signaling logic in kill_proc Miaohe Lin
@ 2022-02-16 9:14 ` Miaohe Lin
2022-02-18 1:13 ` HORIGUCHI NAOYA(堀口 直也)
2022-02-16 9:14 ` [PATCH v2 5/8] mm/memory-failure.c: remove PageSlab check in hwpoison_filter_dev Miaohe Lin
` (3 subsequent siblings)
7 siblings, 1 reply; 11+ messages in thread
From: Miaohe Lin @ 2022-02-16 9:14 UTC (permalink / raw)
To: akpm, naoya.horiguchi; +Cc: linux-mm, linux-kernel, linmiaohe
We're only intended to deal with the non-Compound page after we split thp
in memory_failure. However, the page could have changed compound pages due
to race window. If this happens, we could try again to hopefully handle the
page next round. Also remove unneeded orig_head. It's always equal to the
hpage. So we can use hpage directly and remove this redundant one.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
mm/memory-failure.c | 20 ++++++++++++--------
1 file changed, 12 insertions(+), 8 deletions(-)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 7e205d91b2d7..d66f642888be 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1690,7 +1690,6 @@ int memory_failure(unsigned long pfn, int flags)
{
struct page *p;
struct page *hpage;
- struct page *orig_head;
struct dev_pagemap *pgmap;
int res = 0;
unsigned long page_flags;
@@ -1736,7 +1735,7 @@ int memory_failure(unsigned long pfn, int flags)
goto unlock_mutex;
}
- orig_head = hpage = compound_head(p);
+ hpage = compound_head(p);
num_poisoned_pages_inc();
/*
@@ -1817,13 +1816,18 @@ int memory_failure(unsigned long pfn, int flags)
lock_page(p);
/*
- * The page could have changed compound pages during the locking.
- * If this happens just bail out.
+ * We're only intended to deal with the non-Compound page here.
+ * However, the page could have changed compound pages due to
+ * race window. If this happens, we could try again to hopefully
+ * handle the page next round.
*/
- if (PageCompound(p) && compound_head(p) != orig_head) {
- action_result(pfn, MF_MSG_DIFFERENT_COMPOUND, MF_IGNORED);
- res = -EBUSY;
- goto unlock_page;
+ if (PageCompound(p)) {
+ if (TestClearPageHWPoison(p))
+ num_poisoned_pages_dec();
+ unlock_page(p);
+ put_page(p);
+ flags &= ~MF_COUNT_INCREASED;
+ goto try_again;
}
/*
--
2.23.0
^ permalink raw reply related [flat|nested] 11+ messages in thread
* [PATCH v2 5/8] mm/memory-failure.c: remove PageSlab check in hwpoison_filter_dev
2022-02-16 9:14 [PATCH v2 0/8] A few cleanup and fixup patches for memory failure Miaohe Lin
` (3 preceding siblings ...)
2022-02-16 9:14 ` [PATCH v2 4/8] mm/memory-failure.c: fix race with changing page more robustly Miaohe Lin
@ 2022-02-16 9:14 ` Miaohe Lin
2022-02-16 9:14 ` [PATCH v2 6/8] mm/memory-failure.c: rework the try_to_unmap logic in hwpoison_user_mappings() Miaohe Lin
` (2 subsequent siblings)
7 siblings, 0 replies; 11+ messages in thread
From: Miaohe Lin @ 2022-02-16 9:14 UTC (permalink / raw)
To: akpm, naoya.horiguchi; +Cc: linux-mm, linux-kernel, linmiaohe
Since commit 03e5ac2fc3bf ("mm: fix crash when using XFS on loopback"),
page_mapping() can handle the Slab pages. So remove this unnecessary
PageSlab check and obsolete comment.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
---
mm/memory-failure.c | 6 ------
1 file changed, 6 deletions(-)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index d66f642888be..791d89e0c15a 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -130,12 +130,6 @@ static int hwpoison_filter_dev(struct page *p)
hwpoison_filter_dev_minor == ~0U)
return 0;
- /*
- * page_mapping() does not accept slab pages.
- */
- if (PageSlab(p))
- return -EINVAL;
-
mapping = page_mapping(p);
if (mapping == NULL || mapping->host == NULL)
return -EINVAL;
--
2.23.0
^ permalink raw reply related [flat|nested] 11+ messages in thread
* [PATCH v2 6/8] mm/memory-failure.c: rework the try_to_unmap logic in hwpoison_user_mappings()
2022-02-16 9:14 [PATCH v2 0/8] A few cleanup and fixup patches for memory failure Miaohe Lin
` (4 preceding siblings ...)
2022-02-16 9:14 ` [PATCH v2 5/8] mm/memory-failure.c: remove PageSlab check in hwpoison_filter_dev Miaohe Lin
@ 2022-02-16 9:14 ` Miaohe Lin
2022-02-16 9:14 ` [PATCH v2 7/8] mm/memory-failure.c: remove obsolete comment in __soft_offline_page Miaohe Lin
2022-02-16 9:14 ` [PATCH v2 8/8] mm/memory-failure.c: remove unnecessary PageTransTail check Miaohe Lin
7 siblings, 0 replies; 11+ messages in thread
From: Miaohe Lin @ 2022-02-16 9:14 UTC (permalink / raw)
To: akpm, naoya.horiguchi; +Cc: linux-mm, linux-kernel, linmiaohe
Only for hugetlb pages in shared mappings, try_to_unmap should take
semaphore in write mode here. Rework the code to make it clear.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
---
mm/memory-failure.c | 34 +++++++++++++++-------------------
1 file changed, 15 insertions(+), 19 deletions(-)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 791d89e0c15a..0100d4f9da9a 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1404,26 +1404,22 @@ static bool hwpoison_user_mappings(struct page *p, unsigned long pfn,
if (kill)
collect_procs(hpage, &tokill, flags & MF_ACTION_REQUIRED);
- if (!PageHuge(hpage)) {
- try_to_unmap(hpage, ttu);
+ if (PageHuge(hpage) && !PageAnon(hpage)) {
+ /*
+ * For hugetlb pages in shared mappings, try_to_unmap
+ * could potentially call huge_pmd_unshare. Because of
+ * this, take semaphore in write mode here and set
+ * TTU_RMAP_LOCKED to indicate we have taken the lock
+ * at this higher level.
+ */
+ mapping = hugetlb_page_mapping_lock_write(hpage);
+ if (mapping) {
+ try_to_unmap(hpage, ttu|TTU_RMAP_LOCKED);
+ i_mmap_unlock_write(mapping);
+ } else
+ pr_info("Memory failure: %#lx: could not lock mapping for mapped huge page\n", pfn);
} else {
- if (!PageAnon(hpage)) {
- /*
- * For hugetlb pages in shared mappings, try_to_unmap
- * could potentially call huge_pmd_unshare. Because of
- * this, take semaphore in write mode here and set
- * TTU_RMAP_LOCKED to indicate we have taken the lock
- * at this higher level.
- */
- mapping = hugetlb_page_mapping_lock_write(hpage);
- if (mapping) {
- try_to_unmap(hpage, ttu|TTU_RMAP_LOCKED);
- i_mmap_unlock_write(mapping);
- } else
- pr_info("Memory failure: %#lx: could not lock mapping for mapped huge page\n", pfn);
- } else {
- try_to_unmap(hpage, ttu);
- }
+ try_to_unmap(hpage, ttu);
}
unmap_success = !page_mapped(hpage);
--
2.23.0
^ permalink raw reply related [flat|nested] 11+ messages in thread
* [PATCH v2 7/8] mm/memory-failure.c: remove obsolete comment in __soft_offline_page
2022-02-16 9:14 [PATCH v2 0/8] A few cleanup and fixup patches for memory failure Miaohe Lin
` (5 preceding siblings ...)
2022-02-16 9:14 ` [PATCH v2 6/8] mm/memory-failure.c: rework the try_to_unmap logic in hwpoison_user_mappings() Miaohe Lin
@ 2022-02-16 9:14 ` Miaohe Lin
2022-02-16 9:14 ` [PATCH v2 8/8] mm/memory-failure.c: remove unnecessary PageTransTail check Miaohe Lin
7 siblings, 0 replies; 11+ messages in thread
From: Miaohe Lin @ 2022-02-16 9:14 UTC (permalink / raw)
To: akpm, naoya.horiguchi; +Cc: linux-mm, linux-kernel, linmiaohe
Since commit add05cecef80 ("mm: soft-offline: don't free target page in
successful page migration"), set_migratetype_isolate logic is removed.
Remove this obsolete comment.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
---
mm/memory-failure.c | 4 ----
1 file changed, 4 deletions(-)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 0100d4f9da9a..5d2e653a145d 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -2165,10 +2165,6 @@ static int __soft_offline_page(struct page *page)
ret = invalidate_inode_page(page);
unlock_page(page);
- /*
- * RED-PEN would be better to keep it isolated here, but we
- * would need to fix isolation locking first.
- */
if (ret) {
pr_info("soft_offline: %#lx: invalidated\n", pfn);
page_handle_poison(page, false, true);
--
2.23.0
^ permalink raw reply related [flat|nested] 11+ messages in thread
* [PATCH v2 8/8] mm/memory-failure.c: remove unnecessary PageTransTail check
2022-02-16 9:14 [PATCH v2 0/8] A few cleanup and fixup patches for memory failure Miaohe Lin
` (6 preceding siblings ...)
2022-02-16 9:14 ` [PATCH v2 7/8] mm/memory-failure.c: remove obsolete comment in __soft_offline_page Miaohe Lin
@ 2022-02-16 9:14 ` Miaohe Lin
7 siblings, 0 replies; 11+ messages in thread
From: Miaohe Lin @ 2022-02-16 9:14 UTC (permalink / raw)
To: akpm, naoya.horiguchi; +Cc: linux-mm, linux-kernel, linmiaohe
When we reach here, we're guaranteed to have non-compound page as thp is
already splited. Remove this unnecessary PageTransTail check.
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
---
mm/memory-failure.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 5d2e653a145d..6e7baa90214a 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1842,7 +1842,7 @@ int memory_failure(unsigned long pfn, int flags)
* page_lock. We need wait writeback completion for this page or it
* may trigger vfs BUG while evict inode.
*/
- if (!PageTransTail(p) && !PageLRU(p) && !PageWriteback(p))
+ if (!PageLRU(p) && !PageWriteback(p))
goto identify_page_state;
/*
--
2.23.0
^ permalink raw reply related [flat|nested] 11+ messages in thread
* Re: [PATCH v2 4/8] mm/memory-failure.c: fix race with changing page more robustly
2022-02-16 9:14 ` [PATCH v2 4/8] mm/memory-failure.c: fix race with changing page more robustly Miaohe Lin
@ 2022-02-18 1:13 ` HORIGUCHI NAOYA(堀口 直也)
2022-02-18 1:53 ` Miaohe Lin
0 siblings, 1 reply; 11+ messages in thread
From: HORIGUCHI NAOYA(堀口 直也) @ 2022-02-18 1:13 UTC (permalink / raw)
To: Miaohe Lin; +Cc: akpm, linux-mm, linux-kernel
On Wed, Feb 16, 2022 at 05:14:27PM +0800, Miaohe Lin wrote:
> We're only intended to deal with the non-Compound page after we split thp
> in memory_failure. However, the page could have changed compound pages due
> to race window. If this happens, we could try again to hopefully handle the
> page next round. Also remove unneeded orig_head. It's always equal to the
> hpage. So we can use hpage directly and remove this redundant one.
>
> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
> ---
> mm/memory-failure.c | 20 ++++++++++++--------
> 1 file changed, 12 insertions(+), 8 deletions(-)
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 7e205d91b2d7..d66f642888be 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -1690,7 +1690,6 @@ int memory_failure(unsigned long pfn, int flags)
> {
> struct page *p;
> struct page *hpage;
> - struct page *orig_head;
> struct dev_pagemap *pgmap;
> int res = 0;
> unsigned long page_flags;
> @@ -1736,7 +1735,7 @@ int memory_failure(unsigned long pfn, int flags)
> goto unlock_mutex;
> }
>
> - orig_head = hpage = compound_head(p);
> + hpage = compound_head(p);
> num_poisoned_pages_inc();
>
> /*
> @@ -1817,13 +1816,18 @@ int memory_failure(unsigned long pfn, int flags)
> lock_page(p);
>
> /*
> - * The page could have changed compound pages during the locking.
> - * If this happens just bail out.
> + * We're only intended to deal with the non-Compound page here.
> + * However, the page could have changed compound pages due to
> + * race window. If this happens, we could try again to hopefully
> + * handle the page next round.
> */
> - if (PageCompound(p) && compound_head(p) != orig_head) {
> - action_result(pfn, MF_MSG_DIFFERENT_COMPOUND, MF_IGNORED);
> - res = -EBUSY;
> - goto unlock_page;
> + if (PageCompound(p)) {
> + if (TestClearPageHWPoison(p))
> + num_poisoned_pages_dec();
> + unlock_page(p);
> + put_page(p);
> + flags &= ~MF_COUNT_INCREASED;
Could you limit the retry chance only once by using the local variable
"retry"? It might be very rare to hit the race more than once in a single
error event, but just to be safe from potential infinite loop (that could be
opened by future changes).
Thanks,
Naoya Horiguchi
> + goto try_again;
> }
>
> /*
> --
> 2.23.0
^ permalink raw reply [flat|nested] 11+ messages in thread
* Re: [PATCH v2 4/8] mm/memory-failure.c: fix race with changing page more robustly
2022-02-18 1:13 ` HORIGUCHI NAOYA(堀口 直也)
@ 2022-02-18 1:53 ` Miaohe Lin
0 siblings, 0 replies; 11+ messages in thread
From: Miaohe Lin @ 2022-02-18 1:53 UTC (permalink / raw)
To: HORIGUCHI NAOYA(堀口 直也)
Cc: akpm, linux-mm, linux-kernel
On 2022/2/18 9:13, HORIGUCHI NAOYA(堀口 直也) wrote:
> On Wed, Feb 16, 2022 at 05:14:27PM +0800, Miaohe Lin wrote:
>> We're only intended to deal with the non-Compound page after we split thp
>> in memory_failure. However, the page could have changed compound pages due
>> to race window. If this happens, we could try again to hopefully handle the
>> page next round. Also remove unneeded orig_head. It's always equal to the
>> hpage. So we can use hpage directly and remove this redundant one.
>>
>> Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
>> ---
>> mm/memory-failure.c | 20 ++++++++++++--------
>> 1 file changed, 12 insertions(+), 8 deletions(-)
>>
>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>> index 7e205d91b2d7..d66f642888be 100644
>> --- a/mm/memory-failure.c
>> +++ b/mm/memory-failure.c
>> @@ -1690,7 +1690,6 @@ int memory_failure(unsigned long pfn, int flags)
>> {
>> struct page *p;
>> struct page *hpage;
>> - struct page *orig_head;
>> struct dev_pagemap *pgmap;
>> int res = 0;
>> unsigned long page_flags;
>> @@ -1736,7 +1735,7 @@ int memory_failure(unsigned long pfn, int flags)
>> goto unlock_mutex;
>> }
>>
>> - orig_head = hpage = compound_head(p);
>> + hpage = compound_head(p);
>> num_poisoned_pages_inc();
>>
>> /*
>> @@ -1817,13 +1816,18 @@ int memory_failure(unsigned long pfn, int flags)
>> lock_page(p);
>>
>> /*
>> - * The page could have changed compound pages during the locking.
>> - * If this happens just bail out.
>> + * We're only intended to deal with the non-Compound page here.
>> + * However, the page could have changed compound pages due to
>> + * race window. If this happens, we could try again to hopefully
>> + * handle the page next round.
>> */
>> - if (PageCompound(p) && compound_head(p) != orig_head) {
>> - action_result(pfn, MF_MSG_DIFFERENT_COMPOUND, MF_IGNORED);
>> - res = -EBUSY;
>> - goto unlock_page;
>> + if (PageCompound(p)) {
>> + if (TestClearPageHWPoison(p))
>> + num_poisoned_pages_dec();
>> + unlock_page(p);
>> + put_page(p);
>> + flags &= ~MF_COUNT_INCREASED;
>
> Could you limit the retry chance only once by using the local variable
> "retry"? It might be very rare to hit the race more than once in a single
> error event, but just to be safe from potential infinite loop (that could be
> opened by future changes).
>
Sure. Will do it in V3. Thanks.
> Thanks,
> Naoya Horiguchi
>
>> + goto try_again;
>> }
>>
>> /*
>> --
>> 2.23.0
^ permalink raw reply [flat|nested] 11+ messages in thread
end of thread, other threads:[~2022-02-18 1:53 UTC | newest]
Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-02-16 9:14 [PATCH v2 0/8] A few cleanup and fixup patches for memory failure Miaohe Lin
2022-02-16 9:14 ` [PATCH v2 1/8] mm/memory-failure.c: minor clean up for memory_failure_dev_pagemap Miaohe Lin
2022-02-16 9:14 ` [PATCH v2 2/8] mm/memory-failure.c: catch unexpected -EFAULT from vma_address() Miaohe Lin
2022-02-16 9:14 ` [PATCH v2 3/8] mm/memory-failure.c: rework the signaling logic in kill_proc Miaohe Lin
2022-02-16 9:14 ` [PATCH v2 4/8] mm/memory-failure.c: fix race with changing page more robustly Miaohe Lin
2022-02-18 1:13 ` HORIGUCHI NAOYA(堀口 直也)
2022-02-18 1:53 ` Miaohe Lin
2022-02-16 9:14 ` [PATCH v2 5/8] mm/memory-failure.c: remove PageSlab check in hwpoison_filter_dev Miaohe Lin
2022-02-16 9:14 ` [PATCH v2 6/8] mm/memory-failure.c: rework the try_to_unmap logic in hwpoison_user_mappings() Miaohe Lin
2022-02-16 9:14 ` [PATCH v2 7/8] mm/memory-failure.c: remove obsolete comment in __soft_offline_page Miaohe Lin
2022-02-16 9:14 ` [PATCH v2 8/8] mm/memory-failure.c: remove unnecessary PageTransTail check Miaohe Lin
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