The patch titled
Subject: minor cleanup according to Peter Xu
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-fix-kernel-bug-when-userfaultfd_move-encounters-swapcache-fix.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-fix-kernel-bug-when-userfaultfd_move-encounters-swapcache-fix.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: Barry Song <v-songbaohua@xxxxxxxx>
Subject: minor cleanup according to Peter Xu
Date: Wed, 26 Feb 2025 15:22:17 +1300
According to Peter Xu:
1. Unnecessary line move.
2. Can drop this folio check as it just did check
"!IS_ERR_OR_NULL(folio)"
3. Not sure if it can do any harm, but maybe still nicer
to put swap before locking folio.
Link: https://lkml.kernel.org/r/20250226024411.47092-1-21cnbao@xxxxxxxxx
Signed-off-by: Barry Song <v-songbaohua@xxxxxxxx>
Cc: Peter Xu <peterx@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/userfaultfd.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/mm/userfaultfd.c~mm-fix-kernel-bug-when-userfaultfd_move-encounters-swapcache-fix
+++ a/mm/userfaultfd.c
@@ -1105,8 +1105,8 @@ static int move_swap_pte(struct mm_struc
orig_src_pte = ptep_get_and_clear(mm, src_addr, src_pte);
set_pte_at(mm, dst_addr, dst_pte, orig_src_pte);
-
double_pt_unlock(dst_ptl, src_ptl);
+
return 0;
}
@@ -1373,7 +1373,7 @@ retry:
folio = filemap_get_folio(swap_address_space(entry),
swap_cache_index(entry));
if (!IS_ERR_OR_NULL(folio)) {
- if (folio && folio_test_large(folio)) {
+ if (folio_test_large(folio)) {
err = -EBUSY;
folio_put(folio);
goto out;
@@ -1384,10 +1384,10 @@ retry:
pte_unmap(&orig_src_pte);
pte_unmap(&orig_dst_pte);
src_pte = dst_pte = NULL;
- /* now we can block and wait */
- folio_lock(src_folio);
put_swap_device(si);
si = NULL;
+ /* now we can block and wait */
+ folio_lock(src_folio);
goto retry;
}
}
_
Patches currently in -mm which might be from v-songbaohua@xxxxxxxx are
mm-fix-kernel-bug-when-userfaultfd_move-encounters-swapcache.patch
mm-fix-kernel-bug-when-userfaultfd_move-encounters-swapcache-fix.patch
mm-set-folio-swapbacked-iff-folios-are-dirty-in-try_to_unmap_one.patch
mm-support-tlbbatch-flush-for-a-range-of-ptes.patch
mm-support-batched-unmap-for-lazyfree-large-folios-during-reclamation.patch
mm-avoid-splitting-pmd-for-lazyfree-pmd-mapped-thp-in-try_to_unmap.patch
