This is a note to let you know that I've just added the patch titled
mm,hugetlb: take hugetlb_lock before decrementing h->resv_huge_pages
to the 5.15-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-hugetlb-take-hugetlb_lock-before-decrementing-h-resv_huge_pages.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 12df140f0bdfae5dcfc81800970dd7f6f632e00c Mon Sep 17 00:00:00 2001
From: Rik van Riel <riel@xxxxxxxxxxx>
Date: Mon, 17 Oct 2022 20:25:05 -0400
Subject: mm,hugetlb: take hugetlb_lock before decrementing h->resv_huge_pages
From: Rik van Riel <riel@xxxxxxxxxxx>
commit 12df140f0bdfae5dcfc81800970dd7f6f632e00c upstream.
The h->*_huge_pages counters are protected by the hugetlb_lock, but
alloc_huge_page has a corner case where it can decrement the counter
outside of the lock.
This could lead to a corrupted value of h->resv_huge_pages, which we have
observed on our systems.
Take the hugetlb_lock before decrementing h->resv_huge_pages to avoid a
potential race.
Link: https://lkml.kernel.org/r/20221017202505.0e6a4fcd@xxxxxxxxxxxxxxxxxxxx
Fixes: a88c76954804 ("mm: hugetlb: fix hugepage memory leak caused by wrong reserve count")
Signed-off-by: Rik van Riel <riel@xxxxxxxxxxx>
Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: Glen McCready <gkmccready@xxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -2813,11 +2813,11 @@ struct page *alloc_huge_page(struct vm_a
page = alloc_buddy_huge_page_with_mpol(h, vma, addr);
if (!page)
goto out_uncharge_cgroup;
+ spin_lock_irq(&hugetlb_lock);
if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) {
SetHPageRestoreReserve(page);
h->resv_huge_pages--;
}
- spin_lock_irq(&hugetlb_lock);
list_add(&page->lru, &h->hugepage_activelist);
/* Fall through */
}
Patches currently in stable-queue which might be from riel@xxxxxxxxxxx are
queue-5.15/mm-hugetlb-take-hugetlb_lock-before-decrementing-h-resv_huge_pages.patch
