This is a note to let you know that I've just added the patch titled
mm: add !pte_present() check on existing hugetlb_entry callbacks
to the 3.14-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:
mm-add-pte_present-check-on-existing-hugetlb_entry-callbacks.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d4c54919ed86302094c0ca7d48a8cbd4ee753e92 Mon Sep 17 00:00:00 2001
From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Date: Fri, 6 Jun 2014 10:00:01 -0400
Subject: mm: add !pte_present() check on existing hugetlb_entry callbacks
From: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
commit d4c54919ed86302094c0ca7d48a8cbd4ee753e92 upstream.
The age table walker doesn't check non-present hugetlb entry in common
path, so hugetlb_entry() callbacks must check it. The reason for this
behavior is that some callers want to handle it in its own way.
[ I think that reason is bogus, btw - it should just do what the regular
code does, which is to call the "pte_hole()" function for such hugetlb
entries - Linus]
However, some callers don't check it now, which causes unpredictable
result, for example when we have a race between migrating hugepage and
reading /proc/pid/numa_maps. This patch fixes it by adding !pte_present
checks on buggy callbacks.
This bug exists for years and got visible by introducing hugepage
migration.
ChangeLog v2:
- fix if condition (check !pte_present() instead of pte_present())
Reported-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
Signed-off-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
[ Backported to 3.15. Signed-off-by: Josh Boyer <jwboyer@xxxxxxxxxxxxxxxxx> ]
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 2 +-
mm/mempolicy.c | 6 +++++-
2 files changed, 6 insertions(+), 2 deletions(-)
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -1350,7 +1350,7 @@ static int gather_hugetbl_stats(pte_t *p
struct numa_maps *md;
struct page *page;
- if (pte_none(*pte))
+ if (!pte_present(*pte))
return 0;
page = pte_page(*pte);
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -526,9 +526,13 @@ static void queue_pages_hugetlb_pmd_rang
int nid;
struct page *page;
spinlock_t *ptl;
+ pte_t entry;
ptl = huge_pte_lock(hstate_vma(vma), vma->vm_mm, (pte_t *)pmd);
- page = pte_page(huge_ptep_get((pte_t *)pmd));
+ entry = huge_ptep_get((pte_t *)pmd);
+ if (!pte_present(entry))
+ goto unlock;
+ page = pte_page(entry);
nid = page_to_nid(page);
if (node_isset(nid, *nodes) == !!(flags & MPOL_MF_INVERT))
goto unlock;
Patches currently in stable-queue which might be from n-horiguchi@xxxxxxxxxxxxx are
queue-3.14/mm-add-pte_present-check-on-existing-hugetlb_entry-callbacks.patch
queue-3.14/mm-memory-failure.c-fix-memory-leak-by-race-between-poison-and-unpoison.patch
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