diff options
author | Takashi Iwai <tiwai@suse.de> | 2016-03-08 09:49:43 (GMT) |
---|---|---|
committer | Takashi Iwai <tiwai@suse.de> | 2016-03-08 09:49:43 (GMT) |
commit | 56d94d70398f0fbb1863a03a145db1a86f009a71 (patch) | |
tree | 9e52dc537f8f8359c70b66f5000192bb280b41b9 /mm/memory.c | |
parent | bb63f726f98bec032c7322a9c36eb4167307d856 (diff) | |
parent | fc4f000bf8c0cbf38f44de6bd5e225574e572ed4 (diff) | |
download | linux-56d94d70398f0fbb1863a03a145db1a86f009a71.tar.xz |
Merge branch 'topic/hda' into for-next
Diffstat (limited to 'mm/memory.c')
-rw-r--r-- | mm/memory.c | 14 |
1 files changed, 12 insertions, 2 deletions
diff --git a/mm/memory.c b/mm/memory.c index 635451a..8132787 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3404,8 +3404,18 @@ static int __handle_mm_fault(struct mm_struct *mm, struct vm_area_struct *vma, if (unlikely(pmd_none(*pmd)) && unlikely(__pte_alloc(mm, vma, pmd, address))) return VM_FAULT_OOM; - /* if an huge pmd materialized from under us just retry later */ - if (unlikely(pmd_trans_huge(*pmd) || pmd_devmap(*pmd))) + /* + * If a huge pmd materialized under us just retry later. Use + * pmd_trans_unstable() instead of pmd_trans_huge() to ensure the pmd + * didn't become pmd_trans_huge under us and then back to pmd_none, as + * a result of MADV_DONTNEED running immediately after a huge pmd fault + * in a different thread of this mm, in turn leading to a misleading + * pmd_trans_huge() retval. All we have to ensure is that it is a + * regular pmd that we can walk with pte_offset_map() and we can do that + * through an atomic read in C, which is what pmd_trans_unstable() + * provides. + */ + if (unlikely(pmd_trans_unstable(pmd) || pmd_devmap(*pmd))) return 0; /* * A regular pmd is established and it can't morph into a huge pmd |