Messages in this thread | | | From | Cong Wang <> | Date | Fri, 4 Aug 2017 11:06:03 -0700 | Subject | Re: [PATCH] mm: fix list corruptions on shmem shrinklist |
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On Thu, Aug 3, 2017 at 4:25 PM, Linus Torvalds <torvalds@linux-foundation.org> wrote: > On Thu, Aug 3, 2017 at 4:11 PM, Andrew Morton <akpm@linux-foundation.org> wrote: >> >> Where is this INIT_LIST_HEAD()? > > I think it's this one: > > list_del_init(&info->shrinklist); > > in shmem_unused_huge_shrink().
Yes, this is correct. Sorry about confusion.
> >> I'm not sure I'm understanding this. AFAICT all the list operations to >> which you refer are synchronized under spin_lock(&sbinfo->shrinklist_lock)? > > No, notice how shmem_unused_huge_shrink() does the > > list_move(&info->shrinklist, &to_remove); > > and > > list_move(&info->shrinklist, &list); > > to move to (two different) private lists under the shrinklist_lock, > but once it is on that private "list/to_remove" list, it is then > accessed outside the locked region. > > Honestly, I don't love this situation, or the patch, but I think the > patch is likely the right thing to do. >
Me neither. This is probably the quickest fix we could have, other possible changes might need much more work.
Thanks.
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