The patch titled
Subject: mm-memcg-fix-reclaim-deadlock-with-writeback-fix
has been added to the -mm tree. Its filename is
mm-memcg-fix-reclaim-deadlock-with-writeback-fix.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-memcg-fix-reclaim-deadlock-with-writeback-fix.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-memcg-fix-reclaim-deadlock-with-writeback-fix.patch
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------------------------------------------------------
From: Michal Hocko <mhocko@xxxxxxxxxx>
Subject: mm-memcg-fix-reclaim-deadlock-with-writeback-fix
enhance comment, per Johannes
Link: http://lkml.kernel.org/r/20181214084948.GA5624@xxxxxxxxxxxxxx
Cc: Liu Bo <bo.liu@xxxxxxxxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Jan Kara <jack@xxxxxxx>
Cc: Dave Chinner <david@xxxxxxxxxxxxx>
Cc: Theodore Ts'o <tytso@xxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Cc: Shakeel Butt <shakeelb@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memory.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
--- a/mm/memory.c~mm-memcg-fix-reclaim-deadlock-with-writeback-fix
+++ a/mm/memory.c
@@ -2996,7 +2996,18 @@ static vm_fault_t __do_fault(struct vm_f
/*
* Preallocate pte before we take page_lock because this might lead to
- * deadlocks for memcg reclaim which waits for pages under writeback.
+ * deadlocks for memcg reclaim which waits for pages under writeback:
+ * lock_page(A)
+ * SetPageWriteback(A)
+ * unlock_page(A)
+ * lock_page(B)
+ * lock_page(B)
+ * pte_alloc_pne
+ * shrink_page_list
+ * wait_on_page_writeback(A)
+ * SetPageWriteback(B)
+ * unlock_page(B)
+ * # flush A, B to clear the writeback
*/
if (pmd_none(*vmf->pmd) && !vmf->prealloc_pte) {
vmf->prealloc_pte = pte_alloc_one(vmf->vma->vm_mm, vmf->address);
_
Patches currently in -mm which might be from mhocko@xxxxxxxxxx are
mm-memcg-fix-reclaim-deadlock-with-writeback-fix.patch
