The patch titled
Subject: mm/gup: fix memfd_pin_folios alloc race panic
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-gup-fix-memfd_pin_folios-alloc-race-panic.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-gup-fix-memfd_pin_folios-alloc-race-panic.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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 via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Steve Sistare <steven.sistare@xxxxxxxxxx>
Subject: mm/gup: fix memfd_pin_folios alloc race panic
Date: Tue, 3 Sep 2024 07:25:21 -0700
If memfd_pin_folios tries to create a hugetlb page, but someone else
already did, then folio gets the value -EEXIST here:
folio = memfd_alloc_folio(memfd, start_idx);
if (IS_ERR(folio)) {
ret = PTR_ERR(folio);
if (ret != -EEXIST)
goto err;
then on the next trip through the "while start_idx" loop we panic here:
if (folio) {
folio_put(folio);
To fix, set the folio to NULL on error.
Link: https://lkml.kernel.org/r/1725373521-451395-6-git-send-email-steven.sistare@xxxxxxxxxx
Fixes: 89c1905d9c14 ("mm/gup: introduce memfd_pin_folios() for pinning memfd folios")
Signed-off-by: Steve Sistare <steven.sistare@xxxxxxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Cc: Vivek Kasireddy <vivek.kasireddy@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/gup.c | 1 +
1 file changed, 1 insertion(+)
--- a/mm/gup.c~mm-gup-fix-memfd_pin_folios-alloc-race-panic
+++ a/mm/gup.c
@@ -3705,6 +3705,7 @@ long memfd_pin_folios(struct file *memfd
ret = PTR_ERR(folio);
if (ret != -EEXIST)
goto err;
+ folio = NULL;
}
}
}
_
Patches currently in -mm which might be from steven.sistare@xxxxxxxxxx are
mm-filemap-fix-filemap_get_folios_contig-thp-panic.patch
mm-hugetlb-fix-memfd_pin_folios-free_huge_pages-leak.patch
mm-hugetlb-fix-memfd_pin_folios-resv_huge_pages-leak.patch
mm-gup-fix-memfd_pin_folios-hugetlb-page-allocation.patch
mm-gup-fix-memfd_pin_folios-alloc-race-panic.patch
