The patch titled
Subject: mm: do not reclaim private data from pinned page
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-do-not-reclaim-private-data-from-pinned-page.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-do-not-reclaim-private-data-from-pinned-page.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: Jan Kara <jack@xxxxxxx>
Subject: mm: do not reclaim private data from pinned page
Date: Fri, 28 Apr 2023 14:41:40 +0200
If the page is pinned, there's no point in trying to reclaim it.
Furthermore if the page is from the page cache we don't want to reclaim
fs-private data from the page because the pinning process may be writing
to the page at any time and reclaiming fs private info on a dirty page can
upset the filesystem (see link below).
Link: https://lore.kernel.org/linux-mm/20180103100430.GE4911@xxxxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20230428124140.30166-1-jack@xxxxxxx
Signed-off-by: Jan Kara <jack@xxxxxxx>
Reviewed-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Reviewed-by: Lorenzo Stoakes <lstoakes@xxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Acked-by: Peter Xu <peterx@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmscan.c | 10 ++++++++++
1 file changed, 10 insertions(+)
--- a/mm/vmscan.c~mm-do-not-reclaim-private-data-from-pinned-page
+++ a/mm/vmscan.c
@@ -1967,6 +1967,16 @@ retry:
}
}
+ /*
+ * Folio is unmapped now so it cannot be newly pinned anymore.
+ * No point in trying to reclaim folio if it is pinned.
+ * Furthermore we don't want to reclaim underlying fs metadata
+ * if the folio is pinned and thus potentially modified by the
+ * pinning process as that may upset the filesystem.
+ */
+ if (folio_maybe_dma_pinned(folio))
+ goto activate_locked;
+
mapping = folio_mapping(folio);
if (folio_test_dirty(folio)) {
/*
_
Patches currently in -mm which might be from jack@xxxxxxx are
mm-do-not-reclaim-private-data-from-pinned-page.patch
