diff options
| author | andrew.yang <andrew.yang@mediatek.com> | 2022-03-22 14:46:08 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-03-22 15:57:09 -0700 |
| commit | 356ea3865687926e5da7579d1f3351d3f0a322a1 (patch) | |
| tree | e5f2593aa9013ea269204b789fb3a8fd5bf625d7 /include/linux/page-flags.h | |
| parent | fc89213a636c3735eb3386f10a34c082271b4192 (diff) | |
mm/migrate: fix race between lock page and clear PG_Isolated
When memory is tight, system may start to compact memory for large
continuous memory demands. If one process tries to lock a memory page
that is being locked and isolated for compaction, it may wait a long time
or even forever. This is because compaction will perform non-atomic
PG_Isolated clear while holding page lock, this may overwrite PG_waiters
set by the process that can't obtain the page lock and add itself to the
waiting queue to wait for the lock to be unlocked.
CPU1 CPU2
lock_page(page); (successful)
lock_page(); (failed)
__ClearPageIsolated(page); SetPageWaiters(page) (may be overwritten)
unlock_page(page);
The solution is to not perform non-atomic operation on page flags while
holding page lock.
Link: https://lkml.kernel.org/r/20220315030515.20263-1-andrew.yang@mediatek.com
Signed-off-by: andrew.yang <andrew.yang@mediatek.com>
Cc: Matthias Brugger <matthias.bgg@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: "Vlastimil Babka" <vbabka@suse.cz>
Cc: David Howells <dhowells@redhat.com>
Cc: "William Kucharski" <william.kucharski@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Nicholas Tang <nicholas.tang@mediatek.com>
Cc: Kuan-Ying Lee <Kuan-Ying.Lee@mediatek.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/page-flags.h')
| -rw-r--r-- | include/linux/page-flags.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h index 340cb8156568..88fe1d759cdd 100644 --- a/include/linux/page-flags.h +++ b/include/linux/page-flags.h @@ -1000,7 +1000,7 @@ PAGE_TYPE_OPS(Guard, guard) extern bool is_free_buddy_page(struct page *page); -__PAGEFLAG(Isolated, isolated, PF_ANY); +PAGEFLAG(Isolated, isolated, PF_ANY); #ifdef CONFIG_MMU #define __PG_MLOCKED (1UL << PG_mlocked) |