* Patch "thp: fix MADV_DONTNEED vs. MADV_FREE race" has been added to the 4.10-stable tree
@ 2017-04-18 12:48 gregkh
0 siblings, 0 replies; only message in thread
From: gregkh @ 2017-04-18 12:48 UTC (permalink / raw)
To: kirill.shutemov, aarcange, akpm, gregkh, hillf.zj, minchan, torvalds
Cc: stable, stable-commits
This is a note to let you know that I've just added the patch titled
thp: fix MADV_DONTNEED vs. MADV_FREE race
to the 4.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
thp-fix-madv_dontneed-vs.-madv_free-race.patch
and it can be found in the queue-4.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.
>From 58ceeb6bec86d9140f9d91d71a710e963523d063 Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Date: Thu, 13 Apr 2017 14:56:26 -0700
Subject: thp: fix MADV_DONTNEED vs. MADV_FREE race
From: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
commit 58ceeb6bec86d9140f9d91d71a710e963523d063 upstream.
Both MADV_DONTNEED and MADV_FREE handled with down_read(mmap_sem).
It's critical to not clear pmd intermittently while handling MADV_FREE
to avoid race with MADV_DONTNEED:
CPU0: CPU1:
madvise_free_huge_pmd()
pmdp_huge_get_and_clear_full()
madvise_dontneed()
zap_pmd_range()
pmd_trans_huge(*pmd) == 0 (without ptl)
// skip the pmd
set_pmd_at();
// pmd is re-established
It results in MADV_DONTNEED skipping the pmd, leaving it not cleared.
It violates MADV_DONTNEED interface and can result is userspace
misbehaviour.
Basically it's the same race as with numa balancing in
change_huge_pmd(), but a bit simpler to mitigate: we don't need to
preserve dirty/young flags here due to MADV_FREE functionality.
[kirill.shutemov@linux.intel.com: Urgh... Power is special again]
Link: http://lkml.kernel.org/r/20170303102636.bhd2zhtpds4mt62a@black.fi.intel.com
Link: http://lkml.kernel.org/r/20170302151034.27829-4-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Hillf Danton <hillf.zj@alibaba-inc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
mm/huge_memory.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1393,8 +1393,7 @@ bool madvise_free_huge_pmd(struct mmu_ga
deactivate_page(page);
if (pmd_young(orig_pmd) || pmd_dirty(orig_pmd)) {
- orig_pmd = pmdp_huge_get_and_clear_full(tlb->mm, addr, pmd,
- tlb->fullmm);
+ pmdp_invalidate(vma, addr, pmd);
orig_pmd = pmd_mkold(orig_pmd);
orig_pmd = pmd_mkclean(orig_pmd);
Patches currently in stable-queue which might be from kirill.shutemov@linux.intel.com are
queue-4.10/thp-fix-madv_dontneed-vs-clear-soft-dirty-race.patch
queue-4.10/thp-fix-madv_dontneed-vs.-madv_free-race.patch
^ permalink raw reply [flat|nested] only message in thread
only message in thread, other threads:[~2017-04-18 12:49 UTC | newest]
Thread overview: (only message) (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-04-18 12:48 Patch "thp: fix MADV_DONTNEED vs. MADV_FREE race" has been added to the 4.10-stable tree gregkh
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.