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authorPeter Xu <peterx@redhat.com>2024-04-18 00:18:35 +0300
committerAndrew Morton <akpm@linux-foundation.org>2024-04-25 05:34:25 +0300
commitb76b46902c2d0395488c8412e1116c2486cdfcb2 (patch)
tree2cac9e74a99592a3f3cea9edbf891d88bcd31331
parent6db7412c142006985a15765785cf6c0c0dd75374 (diff)
downloadlinux-b76b46902c2d0395488c8412e1116c2486cdfcb2.tar.xz
mm/hugetlb: fix missing hugetlb_lock for resv uncharge
There is a recent report on UFFDIO_COPY over hugetlb: https://lore.kernel.org/all/000000000000ee06de0616177560@google.com/ 350: lockdep_assert_held(&hugetlb_lock); Should be an issue in hugetlb but triggered in an userfault context, where it goes into the unlikely path where two threads modifying the resv map together. Mike has a fix in that path for resv uncharge but it looks like the locking criteria was overlooked: hugetlb_cgroup_uncharge_folio_rsvd() will update the cgroup pointer, so it requires to be called with the lock held. Link: https://lkml.kernel.org/r/20240417211836.2742593-3-peterx@redhat.com Fixes: 79aa925bf239 ("hugetlb_cgroup: fix reservation accounting") Signed-off-by: Peter Xu <peterx@redhat.com> Reported-by: syzbot+4b8077a5fccc61c385a1@syzkaller.appspotmail.com Reviewed-by: Mina Almasry <almasrymina@google.com> Cc: David Hildenbrand <david@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r--mm/hugetlb.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 31d00eee028f..53e0ab5c0845 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -3268,9 +3268,12 @@ struct folio *alloc_hugetlb_folio(struct vm_area_struct *vma,
rsv_adjust = hugepage_subpool_put_pages(spool, 1);
hugetlb_acct_memory(h, -rsv_adjust);
- if (deferred_reserve)
+ if (deferred_reserve) {
+ spin_lock_irq(&hugetlb_lock);
hugetlb_cgroup_uncharge_folio_rsvd(hstate_index(h),
pages_per_huge_page(h), folio);
+ spin_unlock_irq(&hugetlb_lock);
+ }
}
if (!memcg_charge_ret)