* [PATCH mmotm] mm/vmstat: Add events for PMD based THP migration without split fix
@ 2020-05-21 13:49 Hugh Dickins
2020-05-21 18:54 ` Qian Cai
2020-05-22 0:46 ` Anshuman Khandual
0 siblings, 2 replies; 5+ messages in thread
From: Hugh Dickins @ 2020-05-21 13:49 UTC (permalink / raw)
To: Andrew Morton
Cc: Anshuman Khandual, Naoya Horiguchi, Zi Yan, John Hubbard,
linux-kernel, linux-mm
Fix 5.7-rc6-mm1 page migration crash in unmap_and_move(): when the
page to be migrated has been freed from under us, that is considered
a MIGRATEPAGE_SUCCESS, but no newpage has been allocated (and I don't
think it would ever need to be counted as a successful THP migration).
Signed-off-by: Hugh Dickins <hughd@google.com>
---
Fix to mm-vmstat-add-events-for-pmd-based-thp-migration-without-split.patch
mm/migrate.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- 5.7-rc6-mm1/mm/migrate.c 2020-05-20 12:21:56.117693827 -0700
+++ linux/mm/migrate.c 2020-05-20 15:08:12.319476978 -0700
@@ -1248,7 +1248,7 @@ out:
* we want to retry.
*/
if (rc == MIGRATEPAGE_SUCCESS) {
- if (PageTransHuge(newpage))
+ if (newpage && PageTransHuge(newpage))
thp_migration_success(true);
put_page(page);
if (reason == MR_MEMORY_FAILURE) {
^ permalink raw reply [flat|nested] 5+ messages in thread* Re: [PATCH mmotm] mm/vmstat: Add events for PMD based THP migration without split fix 2020-05-21 13:49 [PATCH mmotm] mm/vmstat: Add events for PMD based THP migration without split fix Hugh Dickins @ 2020-05-21 18:54 ` Qian Cai 2020-05-21 19:48 ` Hugh Dickins 2020-05-22 0:46 ` Anshuman Khandual 1 sibling, 1 reply; 5+ messages in thread From: Qian Cai @ 2020-05-21 18:54 UTC (permalink / raw) To: Hugh Dickins Cc: Andrew Morton, Anshuman Khandual, Johannes Weiner, Naoya Horiguchi, Zi Yan, John Hubbard, linux-kernel, linux-mm On Thu, May 21, 2020 at 06:49:51AM -0700, Hugh Dickins wrote: > Fix 5.7-rc6-mm1 page migration crash in unmap_and_move(): when the > page to be migrated has been freed from under us, that is considered > a MIGRATEPAGE_SUCCESS, but no newpage has been allocated (and I don't > think it would ever need to be counted as a successful THP migration). > > Signed-off-by: Hugh Dickins <hughd@google.com> > --- > Fix to mm-vmstat-add-events-for-pmd-based-thp-migration-without-split.patch > > mm/migrate.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- 5.7-rc6-mm1/mm/migrate.c 2020-05-20 12:21:56.117693827 -0700 > +++ linux/mm/migrate.c 2020-05-20 15:08:12.319476978 -0700 > @@ -1248,7 +1248,7 @@ out: > * we want to retry. > */ > if (rc == MIGRATEPAGE_SUCCESS) { > - if (PageTransHuge(newpage)) > + if (newpage && PageTransHuge(newpage)) Should this be if (!IS_ERR_OR_NULL(newpage) && PageTransHuge(newpage)) ? I have also crashed here due to the buggy commit, unmap_and_move() -> PageTransHuge(page) -> page->compound_head but it said 0x00000008 instead of NULL which is aweful a lot like, https://lore.kernel.org/linux-mm/20200512215813.GA487759@cmpxchg.org/ Interesting thing is I applied this patch and the problem went away, but not sure if it could still be ERR_PTR sometimes just not always? [ 210.929981][ T4159] BUG: Kernel NULL pointer dereference on read at 0x00000008 [ 210.930009][ T4159] Faulting instruction address: 0xc0000000005196c8 [ 210.930027][ C61] irq event stamp: 270727 [ 210.930028][ T4159] Oops: Kernel access of bad area, sig: 11 [#1] [ 210.930033][ T4159] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=256 DEBUG_PAGEALLOC NUMA PowerNV [ 210.930058][ C61] hardirqs last enabled at (270726): [<c000000000adcc44>] _raw_spin_unlock_irqrestore+0x94/0xd0 [ 210.930064][ T4159] Modules linked in: kvm_hv kvm ip_tables x_tables xfs sd_mod tg3 bnx2x libphy mdio firmware_class ahci libahci libata dm_mirror dm_region_hash dm_log dm_mod [ 210.930083][ C61] hardirqs last disabled at (270727): [<c000000000adc8dc>] _raw_spin_lock_irqsave+0x3c/0xa0 [ 210.930086][ C61] softirqs last enabled at (270556): [<c000000000addbdc>] __do_softirq+0x6dc/0xaa8 [ 210.930125][ T4159] CPU: 109 PID: 4159 Comm: test.sh Not tainted 5.7.0-rc6-next-20200521+ #112 [ 210.930163][ C61] softirqs last disabled at (270559): [<c000000000129544>] run_ksoftirqd+0x74/0xc0 [ 210.930260][ T4159] NIP: c0000000005196c8 LR: c000000000519568 CTR: 0000000000000000 [ 210.930307][ T4159] REGS: c0002005b10af570 TRAP: 0300 Not tainted (5.7.0-rc6-next-20200521+) [ 210.930342][ T4159] MSR: 900000000280b033 <SF,HV,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 24248242 XER: 00000000 [ 210.930403][ T4159] CFAR: c000000000519570 DAR: 0000000000000008 DSISR: 40000000 IRQMASK: 0 [ 210.930403][ T4159] GPR00: c000000000519568 c0002005b10af800 c000000001765500 0000000000000000 [ 210.930403][ T4159] GPR04: c000000001c18d28 0000000000000006 0000000035279396 fffffffef69809d2 [ 210.930403][ T4159] GPR08: 0000201cc6240000 0000000000000000 0000000000000000 0000000000000008 [ 210.930403][ T4159] GPR12: 0000000000008000 c000201fff670600 0000000000000000 c00c000805312a00 [ 210.930403][ T4159] GPR16: c00000000050b090 c000000000c857d0 c00c000805312a80 0000000000000000 [ 210.930403][ T4159] GPR20: 0000000000000001 0000000000000000 c0002005b10af978 c000201ffc7c8780 [ 210.930403][ T4159] GPR24: fffffffffffffff5 0000000000000002 0000000020000000 0000000000000000 [ 210.930403][ T4159] GPR28: 0000000000000007 0000000000000001 0000000000000000 c00c000805312a08 [ 210.930740][ T4159] NIP [c0000000005196c8] migrate_pages+0xc18/0x1ad0 [ 210.930775][ T4159] LR [c000000000519568] migrate_pages+0xab8/0x1ad0 [ 210.930824][ T4159] Call Trace: [ 210.930843][ T4159] [c0002005b10af800] [c000000000519568] migrate_pages+0xab8/0x1ad0 (unreliable) [ 210.930882][ T4159] [c0002005b10af910] [c00000000050b6fc] do_migrate_range+0x25c/0x8f0 [ 210.930940][ T4159] [c0002005b10afa10] [c00000000050e974] __offline_pages+0x6e4/0x8b0 [ 210.930988][ T4159] [c0002005b10afb40] [c000000000887f6c] memory_block_action+0xac/0xc0 [ 210.931016][ T4159] [c0002005b10afba0] [c000000000888618] memory_subsys_offline+0x58/0xa0 [ 210.931030][ T4159] [c0002005b10afbd0] [c0000000008621a0] device_offline+0x100/0x140 [ 210.931080][ T4159] [c0002005b10afc10] [c000000000888938] state_store+0x108/0x190 [ 210.931128][ T4159] [c0002005b10afc50] [c00000000085b628] dev_attr_store+0x38/0x60 [ 210.931176][ T4159] [c0002005b10afc70] [c0000000006b9790] sysfs_kf_write+0x70/0xb0 [ 210.931211][ T4159] [c0002005b10afcb0] [c0000000006b895c] kernfs_fop_write+0x11c/0x270 [ 210.931249][ T4159] [c0002005b10afd00] [c00000000057bcac] __vfs_write+0x3c/0x70 [ 210.931273][ T4159] [c0002005b10afd20] [c00000000057f0ac] vfs_write+0xcc/0x200 [ 210.931319][ T4159] [c0002005b10afd70] [c00000000057f44c] ksys_write+0x7c/0x140 [ 210.931345][ T4159] [c0002005b10afdc0] [c000000000039e78] system_call_exception+0x108/0x1d0 [ 210.931395][ T4159] [c0002005b10afe20] [c00000000000c9f0] system_call_common+0xf0/0x278 [ 210.931445][ T4159] Instruction dump: [ 210.931476][ T4159] 9bad0988 e90d0028 3d22ff9f 3929c670 7d49402a 394a0001 7d49412a 4bafdec5 [ 210.931492][ T4159] 60000000 4bfff544 2fbe0000 409e04c4 <e93b0008> 71290001 40820928 e93b0000 [ 210.931521][ T4159] ---[ end trace 03092b3800dbb5cb ]--- [ 211.416724][ T4159] [ 212.416810][ T4159] Kernel panic - not syncing: Fatal exception [ 213.829268][ T4159] ---[ end Kernel panic - not syncing: Fatal exception ]--- > thp_migration_success(true); > put_page(page); > if (reason == MR_MEMORY_FAILURE) { > ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH mmotm] mm/vmstat: Add events for PMD based THP migration without split fix 2020-05-21 18:54 ` Qian Cai @ 2020-05-21 19:48 ` Hugh Dickins 0 siblings, 0 replies; 5+ messages in thread From: Hugh Dickins @ 2020-05-21 19:48 UTC (permalink / raw) To: Qian Cai Cc: Hugh Dickins, Andrew Morton, Anshuman Khandual, Johannes Weiner, Naoya Horiguchi, Zi Yan, John Hubbard, linux-kernel, linux-mm On Thu, 21 May 2020, Qian Cai wrote: > On Thu, May 21, 2020 at 06:49:51AM -0700, Hugh Dickins wrote: > > Fix 5.7-rc6-mm1 page migration crash in unmap_and_move(): when the > > page to be migrated has been freed from under us, that is considered > > a MIGRATEPAGE_SUCCESS, but no newpage has been allocated (and I don't > > think it would ever need to be counted as a successful THP migration). > > > > Signed-off-by: Hugh Dickins <hughd@google.com> > > --- > > Fix to mm-vmstat-add-events-for-pmd-based-thp-migration-without-split.patch > > > > mm/migrate.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > --- 5.7-rc6-mm1/mm/migrate.c 2020-05-20 12:21:56.117693827 -0700 > > +++ linux/mm/migrate.c 2020-05-20 15:08:12.319476978 -0700 > > @@ -1248,7 +1248,7 @@ out: > > * we want to retry. > > */ > > if (rc == MIGRATEPAGE_SUCCESS) { > > - if (PageTransHuge(newpage)) > > + if (newpage && PageTransHuge(newpage)) > > Should this be > > if (!IS_ERR_OR_NULL(newpage) && PageTransHuge(newpage)) ? No: newpage is set higher up by: newpage = get_new_page(page, private); if (!newpage) return -ENOMEM; and there's enough other places after that which would crash on an erroneous newpage. (Of course, the get_new_page() convention might be changed in future to return an error code, but no need to make such a change here and now.) > > I have also crashed here due to the buggy commit, > > unmap_and_move() -> PageTransHuge(page) -> page->compound_head > > but it said 0x00000008 instead of NULL which is aweful a lot like, 0x00000008 is where it's trying to dereference NULL->compound_head, no mystery there. > > https://lore.kernel.org/linux-mm/20200512215813.GA487759@cmpxchg.org/ > > Interesting thing is I applied this patch and the problem went away, but not > sure if it could still be ERR_PTR sometimes just not always? > > [ 210.929981][ T4159] BUG: Kernel NULL pointer dereference on read at 0x00000008 > [ 210.930009][ T4159] Faulting instruction address: 0xc0000000005196c8 > [ 210.930027][ C61] irq event stamp: 270727 > [ 210.930028][ T4159] Oops: Kernel access of bad area, sig: 11 [#1] > [ 210.930033][ T4159] LE PAGE_SIZE=64K MMU=Radix SMP NR_CPUS=256 DEBUG_PAGEALLOC NUMA PowerNV > [ 210.930058][ C61] hardirqs last enabled at (270726): [<c000000000adcc44>] _raw_spin_unlock_irqrestore+0x94/0xd0 > [ 210.930064][ T4159] Modules linked in: kvm_hv kvm ip_tables x_tables xfs sd_mod tg3 bnx2x libphy mdio firmware_class ahci libahci libata dm_mirror dm_region_hash dm_log dm_mod > [ 210.930083][ C61] hardirqs last disabled at (270727): [<c000000000adc8dc>] _raw_spin_lock_irqsave+0x3c/0xa0 > [ 210.930086][ C61] softirqs last enabled at (270556): [<c000000000addbdc>] __do_softirq+0x6dc/0xaa8 > [ 210.930125][ T4159] CPU: 109 PID: 4159 Comm: test.sh Not tainted 5.7.0-rc6-next-20200521+ #112 > [ 210.930163][ C61] softirqs last disabled at (270559): [<c000000000129544>] run_ksoftirqd+0x74/0xc0 > [ 210.930260][ T4159] NIP: c0000000005196c8 LR: c000000000519568 CTR: 0000000000000000 > [ 210.930307][ T4159] REGS: c0002005b10af570 TRAP: 0300 Not tainted (5.7.0-rc6-next-20200521+) > [ 210.930342][ T4159] MSR: 900000000280b033 <SF,HV,VEC,VSX,EE,FP,ME,IR,DR,RI,LE> CR: 24248242 XER: 00000000 > [ 210.930403][ T4159] CFAR: c000000000519570 DAR: 0000000000000008 DSISR: 40000000 IRQMASK: 0 > [ 210.930403][ T4159] GPR00: c000000000519568 c0002005b10af800 c000000001765500 0000000000000000 > [ 210.930403][ T4159] GPR04: c000000001c18d28 0000000000000006 0000000035279396 fffffffef69809d2 > [ 210.930403][ T4159] GPR08: 0000201cc6240000 0000000000000000 0000000000000000 0000000000000008 > [ 210.930403][ T4159] GPR12: 0000000000008000 c000201fff670600 0000000000000000 c00c000805312a00 > [ 210.930403][ T4159] GPR16: c00000000050b090 c000000000c857d0 c00c000805312a80 0000000000000000 > [ 210.930403][ T4159] GPR20: 0000000000000001 0000000000000000 c0002005b10af978 c000201ffc7c8780 > [ 210.930403][ T4159] GPR24: fffffffffffffff5 0000000000000002 0000000020000000 0000000000000000 > [ 210.930403][ T4159] GPR28: 0000000000000007 0000000000000001 0000000000000000 c00c000805312a08 > [ 210.930740][ T4159] NIP [c0000000005196c8] migrate_pages+0xc18/0x1ad0 > [ 210.930775][ T4159] LR [c000000000519568] migrate_pages+0xab8/0x1ad0 > [ 210.930824][ T4159] Call Trace: > [ 210.930843][ T4159] [c0002005b10af800] [c000000000519568] migrate_pages+0xab8/0x1ad0 (unreliable) > [ 210.930882][ T4159] [c0002005b10af910] [c00000000050b6fc] do_migrate_range+0x25c/0x8f0 > [ 210.930940][ T4159] [c0002005b10afa10] [c00000000050e974] __offline_pages+0x6e4/0x8b0 > [ 210.930988][ T4159] [c0002005b10afb40] [c000000000887f6c] memory_block_action+0xac/0xc0 > [ 210.931016][ T4159] [c0002005b10afba0] [c000000000888618] memory_subsys_offline+0x58/0xa0 > [ 210.931030][ T4159] [c0002005b10afbd0] [c0000000008621a0] device_offline+0x100/0x140 > [ 210.931080][ T4159] [c0002005b10afc10] [c000000000888938] state_store+0x108/0x190 > [ 210.931128][ T4159] [c0002005b10afc50] [c00000000085b628] dev_attr_store+0x38/0x60 > [ 210.931176][ T4159] [c0002005b10afc70] [c0000000006b9790] sysfs_kf_write+0x70/0xb0 > [ 210.931211][ T4159] [c0002005b10afcb0] [c0000000006b895c] kernfs_fop_write+0x11c/0x270 > [ 210.931249][ T4159] [c0002005b10afd00] [c00000000057bcac] __vfs_write+0x3c/0x70 > [ 210.931273][ T4159] [c0002005b10afd20] [c00000000057f0ac] vfs_write+0xcc/0x200 > [ 210.931319][ T4159] [c0002005b10afd70] [c00000000057f44c] ksys_write+0x7c/0x140 > [ 210.931345][ T4159] [c0002005b10afdc0] [c000000000039e78] system_call_exception+0x108/0x1d0 > [ 210.931395][ T4159] [c0002005b10afe20] [c00000000000c9f0] system_call_common+0xf0/0x278 > [ 210.931445][ T4159] Instruction dump: > [ 210.931476][ T4159] 9bad0988 e90d0028 3d22ff9f 3929c670 7d49402a 394a0001 7d49412a 4bafdec5 > [ 210.931492][ T4159] 60000000 4bfff544 2fbe0000 409e04c4 <e93b0008> 71290001 40820928 e93b0000 > [ 210.931521][ T4159] ---[ end trace 03092b3800dbb5cb ]--- > [ 211.416724][ T4159] > [ 212.416810][ T4159] Kernel panic - not syncing: Fatal exception > [ 213.829268][ T4159] ---[ end Kernel panic - not syncing: Fatal exception ]--- > > > thp_migration_success(true); > > put_page(page); > > if (reason == MR_MEMORY_FAILURE) { > > ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH mmotm] mm/vmstat: Add events for PMD based THP migration without split fix 2020-05-21 13:49 [PATCH mmotm] mm/vmstat: Add events for PMD based THP migration without split fix Hugh Dickins 2020-05-21 18:54 ` Qian Cai @ 2020-05-22 0:46 ` Anshuman Khandual 2020-05-22 1:21 ` Hugh Dickins 1 sibling, 1 reply; 5+ messages in thread From: Anshuman Khandual @ 2020-05-22 0:46 UTC (permalink / raw) To: Hugh Dickins, Andrew Morton Cc: Naoya Horiguchi, Zi Yan, John Hubbard, linux-kernel, linux-mm On 05/21/2020 07:19 PM, Hugh Dickins wrote: > Fix 5.7-rc6-mm1 page migration crash in unmap_and_move(): when the > page to be migrated has been freed from under us, that is considered > a MIGRATEPAGE_SUCCESS, but no newpage has been allocated (and I don't > think it would ever need to be counted as a successful THP migration). > > Signed-off-by: Hugh Dickins <hughd@google.com> > --- > Fix to mm-vmstat-add-events-for-pmd-based-thp-migration-without-split.patch > > mm/migrate.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > --- 5.7-rc6-mm1/mm/migrate.c 2020-05-20 12:21:56.117693827 -0700 > +++ linux/mm/migrate.c 2020-05-20 15:08:12.319476978 -0700 > @@ -1248,7 +1248,7 @@ out: > * we want to retry. > */ > if (rc == MIGRATEPAGE_SUCCESS) { > - if (PageTransHuge(newpage)) > + if (newpage && PageTransHuge(newpage)) > thp_migration_success(true); > put_page(page); > if (reason == MR_MEMORY_FAILURE) { > Thanks Hugh. I am preparing to respin the vmstat patch accommodating some earlier comments. Wondering if I should also fold these changes here after adding your signed-off-by ? - Anshuman ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH mmotm] mm/vmstat: Add events for PMD based THP migration without split fix 2020-05-22 0:46 ` Anshuman Khandual @ 2020-05-22 1:21 ` Hugh Dickins 0 siblings, 0 replies; 5+ messages in thread From: Hugh Dickins @ 2020-05-22 1:21 UTC (permalink / raw) To: Anshuman Khandual Cc: Hugh Dickins, Andrew Morton, Naoya Horiguchi, Zi Yan, John Hubbard, linux-kernel, linux-mm On Fri, 22 May 2020, Anshuman Khandual wrote: > On 05/21/2020 07:19 PM, Hugh Dickins wrote: > > Fix 5.7-rc6-mm1 page migration crash in unmap_and_move(): when the > > page to be migrated has been freed from under us, that is considered > > a MIGRATEPAGE_SUCCESS, but no newpage has been allocated (and I don't > > think it would ever need to be counted as a successful THP migration). > > > > Signed-off-by: Hugh Dickins <hughd@google.com> > > --- > > Fix to mm-vmstat-add-events-for-pmd-based-thp-migration-without-split.patch > > > > mm/migrate.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > --- 5.7-rc6-mm1/mm/migrate.c 2020-05-20 12:21:56.117693827 -0700 > > +++ linux/mm/migrate.c 2020-05-20 15:08:12.319476978 -0700 > > @@ -1248,7 +1248,7 @@ out: > > * we want to retry. > > */ > > if (rc == MIGRATEPAGE_SUCCESS) { > > - if (PageTransHuge(newpage)) > > + if (newpage && PageTransHuge(newpage)) > > thp_migration_success(true); > > put_page(page); > > if (reason == MR_MEMORY_FAILURE) { > > > > Thanks Hugh. I am preparing to respin the vmstat patch accommodating some > earlier comments. Wondering if I should also fold these changes here after > adding your signed-off-by ? Thanks for asking, but please just fold this one-line fixup into your respin without my signed-off-by: I'm not heavily invested in these stats, just want to avoid the crash; and don't know if I would want to sign the result. You could add something like [hughd: fixed oops on NULL newpage] to confirm that the fix is on board, but the fix is what matters. Hugh ^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2020-05-22 1:22 UTC | newest] Thread overview: 5+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-05-21 13:49 [PATCH mmotm] mm/vmstat: Add events for PMD based THP migration without split fix Hugh Dickins 2020-05-21 18:54 ` Qian Cai 2020-05-21 19:48 ` Hugh Dickins 2020-05-22 0:46 ` Anshuman Khandual 2020-05-22 1:21 ` Hugh Dickins
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