The patch titled
Subject: mm/migrate.c: fix refcount handling when !hugepage_migration_supported()
has been added to the -mm tree. Its filename is
mm-migrate-fix-ref-count-handling-when-hugepage_migration_supported.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-migrate-fix-ref-count-handling-when-hugepage_migration_supported.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-migrate-fix-ref-count-handling-when-hugepage_migration_supported.patch
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------------------------------------------------------
From: Punit Agrawal <punit.agrawal@xxxxxxx>
Subject: mm/migrate.c: fix refcount handling when !hugepage_migration_supported()
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().
Link: http://lkml.kernel.org/r/20170524154728.2492-1-punit.agrawal@xxxxxxx
Fixes: 32665f2bbfed ("mm/migrate: correct failure handling if !hugepage_migration_support()")
Reported-by: Manoj Iyer <manoj.iyer@xxxxxxxxxxxxx>
Signed-off-by: Punit Agrawal <punit.agrawal@xxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/migrate.c | 4 +---
1 file changed, 1 insertion(+), 3 deletions(-)
diff -puN mm/migrate.c~mm-migrate-fix-ref-count-handling-when-hugepage_migration_supported mm/migrate.c
--- a/mm/migrate.c~mm-migrate-fix-ref-count-handling-when-hugepage_migration_supported
+++ a/mm/migrate.c
@@ -1201,10 +1201,8 @@ static int unmap_and_move_huge_page(new_
* 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)
_
Patches currently in -mm which might be from punit.agrawal@xxxxxxx are
mm-migrate-fix-ref-count-handling-when-hugepage_migration_supported.patch
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