The patch below does not apply to the 6.1-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <stable@xxxxxxxxxxxxxxx>. To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y git checkout FETCH_HEAD git cherry-pick -x b76b46902c2d0395488c8412e1116c2486cdfcb2 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to '<stable@xxxxxxxxxxxxxxx>' --in-reply-to '2024042948-overstuff-untwist-805f@gregkh' --subject-prefix 'PATCH 6.1.y' HEAD^.. Possible dependencies: b76b46902c2d ("mm/hugetlb: fix missing hugetlb_lock for resv uncharge") d4ab0316cc33 ("mm/hugetlb_cgroup: convert hugetlb_cgroup_uncharge_page() to folios") 0356c4b96f68 ("mm/hugetlb: convert free_huge_page to folios") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From b76b46902c2d0395488c8412e1116c2486cdfcb2 Mon Sep 17 00:00:00 2001 From: Peter Xu <peterx@xxxxxxxxxx> Date: Wed, 17 Apr 2024 17:18:35 -0400 Subject: [PATCH] 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@xxxxxxxxxx/ 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@xxxxxxxxxx Fixes: 79aa925bf239 ("hugetlb_cgroup: fix reservation accounting") Signed-off-by: Peter Xu <peterx@xxxxxxxxxx> Reported-by: syzbot+4b8077a5fccc61c385a1@xxxxxxxxxxxxxxxxxxxxxxxxx Reviewed-by: Mina Almasry <almasrymina@xxxxxxxxxx> Cc: David Hildenbrand <david@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> 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)
