+ mm-hugetlb-fix-a-race-between-isolating-and-freeing-page.patch added to -mm tree

* + mm-hugetlb-fix-a-race-between-isolating-and-freeing-page.patch added to -mm tree
@ 2021-01-17 20:56 akpm
  0 siblings, 0 replies; 2+ messages in thread
From: akpm @ 2021-01-17 20:56 UTC (permalink / raw)
  To: david, mhocko, mike.kravetz, mm-commits, osalvador, shy828301,
	songmuchun, stable


The patch titled
     Subject: mm: hugetlb: fix a race between isolating and freeing page
has been added to the -mm tree.  Its filename is
     mm-hugetlb-fix-a-race-between-isolating-and-freeing-page.patch

This patch should soon appear at
    https://ozlabs.org/~akpm/mmots/broken-out/mm-hugetlb-fix-a-race-between-isolating-and-freeing-page.patch
and later at
    https://ozlabs.org/~akpm/mmotm/broken-out/mm-hugetlb-fix-a-race-between-isolating-and-freeing-page.patch

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next and is updated
there every 3-4 working days

------------------------------------------------------
From: Muchun Song <songmuchun@bytedance.com>
Subject: mm: hugetlb: fix a race between isolating and freeing page

There is a race between isolate_huge_page() and __free_huge_page().

CPU0:                                       CPU1:

if (PageHuge(page))
                                            put_page(page)
                                              __free_huge_page(page)
                                                  spin_lock(&hugetlb_lock)
                                                  update_and_free_page(page)
                                                    set_compound_page_dtor(page,
                                                      NULL_COMPOUND_DTOR)
                                                  spin_unlock(&hugetlb_lock)
  isolate_huge_page(page)
    // trigger BUG_ON
    VM_BUG_ON_PAGE(!PageHead(page), page)
    spin_lock(&hugetlb_lock)
    page_huge_active(page)
      // trigger BUG_ON
      VM_BUG_ON_PAGE(!PageHuge(page), page)
    spin_unlock(&hugetlb_lock)

When we isolate a HugeTLB page on CPU0. Meanwhile, we free it to the
buddy allocator on CPU1. Then, we can trigger a BUG_ON on CPU0. Because
it is already freed to the buddy allocator.

Link: https://lkml.kernel.org/r/20210115124942.46403-5-songmuchun@bytedance.com
Fixes: c8721bbbdd36 ("mm: memory-hotplug: enable memory hotplug to handle hugepage")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/hugetlb.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/mm/hugetlb.c~mm-hugetlb-fix-a-race-between-isolating-and-freeing-page
+++ a/mm/hugetlb.c
@@ -5594,9 +5594,9 @@ bool isolate_huge_page(struct page *page
 {
 	bool ret = true;
 
-	VM_BUG_ON_PAGE(!PageHead(page), page);
 	spin_lock(&hugetlb_lock);
-	if (!page_huge_active(page) || !get_page_unless_zero(page)) {
+	if (!PageHeadHuge(page) || !page_huge_active(page) ||
+	    !get_page_unless_zero(page)) {
 		ret = false;
 		goto unlock;
 	}
_

Patches currently in -mm which might be from songmuchun@bytedance.com are

mm-hugetlbfs-fix-cannot-migrate-the-fallocated-hugetlb-page.patch
mm-hugetlb-fix-a-race-between-freeing-and-dissolving-the-page.patch
mm-hugetlb-fix-a-race-between-isolating-and-freeing-page.patch
mm-hugetlb-remove-vm_bug_on_page-from-page_huge_active.patch
mm-migrate-do-not-migrate-hugetlb-page-whose-refcount-is-one.patch
mm-memcontrol-optimize-per-lruvec-stats-counter-memory-usage.patch
mm-memcontrol-fix-nr_anon_thps-accounting-in-charge-moving.patch
mm-memcontrol-convert-nr_anon_thps-account-to-pages.patch
mm-memcontrol-convert-nr_file_thps-account-to-pages.patch
mm-memcontrol-convert-nr_shmem_thps-account-to-pages.patch
mm-memcontrol-convert-nr_shmem_pmdmapped-account-to-pages.patch
mm-memcontrol-convert-nr_file_pmdmapped-account-to-pages.patch
mm-memcontrol-make-the-slab-calculation-consistent.patch


^ permalink raw reply	[flat|nested] 2+ messages in thread