This is a note to let you know that I've just added the patch titled
khugepaged: collapse_pte_mapped_thp() flush the right range
to the 5.7-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:
khugepaged-collapse_pte_mapped_thp-flush-the-right-range.patch
and it can be found in the queue-5.7 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 723a80dafed5c95889d48baab9aa433a6ffa0b4e Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hughd@xxxxxxxxxx>
Date: Thu, 6 Aug 2020 23:26:15 -0700
Subject: khugepaged: collapse_pte_mapped_thp() flush the right range
From: Hugh Dickins <hughd@xxxxxxxxxx>
commit 723a80dafed5c95889d48baab9aa433a6ffa0b4e upstream.
pmdp_collapse_flush() should be given the start address at which the huge
page is mapped, haddr: it was given addr, which at that point has been
used as a local variable, incremented to the end address of the extent.
Found by source inspection while chasing a hugepage locking bug, which I
then could not explain by this. At first I thought this was very bad;
then saw that all of the page translations that were not flushed would
actually still point to the right pages afterwards, so harmless; then
realized that I know nothing of how different architectures and models
cache intermediate paging structures, so maybe it matters after all -
particularly since the page table concerned is immediately freed.
Much easier to fix than to think about.
Fixes: 27e1f8273113 ("khugepaged: enable collapse pmd for pte-mapped THP")
Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Song Liu <songliubraving@xxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [5.4+]
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008021204390.27773@eggly.anvils
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/khugepaged.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1403,7 +1403,7 @@ void collapse_pte_mapped_thp(struct mm_s
/* step 4: collapse pmd */
ptl = pmd_lock(vma->vm_mm, pmd);
- _pmd = pmdp_collapse_flush(vma, addr, pmd);
+ _pmd = pmdp_collapse_flush(vma, haddr, pmd);
spin_unlock(ptl);
mm_dec_nr_ptes(mm);
pte_free(mm, pmd_pgtable(_pmd));
Patches currently in stable-queue which might be from hughd@xxxxxxxxxx are
queue-5.7/khugepaged-collapse_pte_mapped_thp-flush-the-right-range.patch
queue-5.7/hugetlbfs-remove-call-to-huge_pte_alloc-without-i_mmap_rwsem.patch
queue-5.7/khugepaged-collapse_pte_mapped_thp-protect-the-pmd-lock.patch
