The patch below does not apply to the v5.15-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@vger.kernel.org.

Thanks, Sasha

------------------ original commit in Linus's tree ------------------

From 41e192ad2779cae0102879612dfe46726e4396aa Mon Sep 17 00:00:00 2001 From: Ryusuke Konishi konishi.ryusuke@gmail.com Date: Fri, 18 Oct 2024 04:33:10 +0900 Subject: [PATCH] nilfs2: fix kernel bug due to missing clearing of checked flag

Syzbot reported that in directory operations after nilfs2 detects filesystem corruption and degrades to read-only, __block_write_begin_int(), which is called to prepare block writes, may fail the BUG_ON check for accesses exceeding the folio/page size, triggering a kernel bug.

This was found to be because the "checked" flag of a page/folio was not cleared when it was discarded by nilfs2's own routine, which causes the sanity check of directory entries to be skipped when the directory page/folio is reloaded. So, fix that.

This was necessary when the use of nilfs2's own page discard routine was applied to more than just metadata files.

Link: https://lkml.kernel.org/r/20241017193359.5051-1-konishi.ryusuke@gmail.com Fixes: 8c26c4e2694a ("nilfs2: fix issue with flush kernel thread after remount in RO mode because of driver's internal error or metadata corruption") Signed-off-by: Ryusuke Konishi konishi.ryusuke@gmail.com Reported-by: syzbot+d6ca2daf692c7a82f959@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=d6ca2daf692c7a82f959 Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org --- fs/nilfs2/page.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/fs/nilfs2/page.c b/fs/nilfs2/page.c index 5436eb0424bd1..10def4b559956 100644 --- a/fs/nilfs2/page.c +++ b/fs/nilfs2/page.c @@ -401,6 +401,7 @@ void nilfs_clear_folio_dirty(struct folio *folio)

folio_clear_uptodate(folio); folio_clear_mappedtodisk(folio); + folio_clear_checked(folio);

head = folio_buffers(folio); if (head) {