From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A0A0B38AC99; Sat, 17 Oct 2026 17:23:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792257802; cv=none; b=iH5d7Emrl+xEHe+wE7lR0fnat9cmjusQNoL0eJoFMuhbcWma5MOQdDyWc+XpW9YHABHpYhhNYGybuPiCIrXGIAA4TQ6fgPcmRWvKE4eM92k5m1IyO8pezF7IuVMjzkASIfq74CVba3rVaGldTJMQeMwOVVIT+swKAuSTxUp3BhA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792257802; c=relaxed/simple; bh=F/C/Qx3/zbm5NFtPrbGwQVNwRolDZ5fvUDVCKemZdno=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cZa3ZvP0LeCFZW/6+7GLJhhAxAnvjaYHICPBXtXlWR2eeq+2igyYK085sXS3HemGZ10zuKCu7oaG8H7DxmrfTkmNIz6i+iV2r9cDcvibpsBTDKUDaiTHaM51y0UJyo6VPCrwn8xCueIc63L7F5whyZ3SfDnoByMcHIWIFyqfquU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=e+JO4BZN; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="e+JO4BZN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EC4EF1F000C4; Sat, 17 Oct 2026 17:23:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792257801; bh=gwejTdPXBbO1wEHPA909dSZOd64E9ee3W1f7VNk7ygQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=e+JO4BZNIBgULbTSqjRCj2vMDZuAjkIR84QW2+PJDNakbIDOchZNezRJQ0W6nF2Nk U6MJmdbcZ6FOArD7k3IviSiw3pEFFkzlfXb+7W/laedCVrOVTQm5vCgUzG0yqb/Ksz WUKmCAFEzTtTWqXny2gCYERuJWIpasZYxje/VxQo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Ryusuke Konishi , syzbot+b2b14916b77acf8626d7@syzkaller.appspotmail.com, syzbot+d98fd19acd08b36ff422@syzkaller.appspotmail.com, Andrew Morton , Sasha Levin Subject: [PATCH 6.6 0676/1674] nilfs2: do not force clear folio if buffer is referenced Date: Sat, 17 Oct 2026 17:49:08 +0200 Message-ID: <20261017160448.460117248@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261017160431.119607952@linuxfoundation.org> References: <20261017160431.119607952@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ryusuke Konishi [ Upstream commit ca76bb226bf47ff04c782cacbd299f12ddee1ec1 ] Patch series "nilfs2: protect busy buffer heads from being force-cleared". This series fixes the buffer head state inconsistency issues reported by syzbot that occurs when the filesystem is corrupted and falls back to read-only, and the associated buffer head use-after-free issue. This patch (of 2): Syzbot has reported that after nilfs2 detects filesystem corruption and falls back to read-only, inconsistencies in the buffer state may occur. One of the inconsistencies is that when nilfs2 calls mark_buffer_dirty() to set a data or metadata buffer as dirty, but it detects that the buffer is not in the uptodate state: WARNING: CPU: 0 PID: 6049 at fs/buffer.c:1177 mark_buffer_dirty+0x2e5/0x520 fs/buffer.c:1177 ... Call Trace: nilfs_palloc_commit_alloc_entry+0x4b/0x160 fs/nilfs2/alloc.c:598 nilfs_ifile_create_inode+0x1dd/0x3a0 fs/nilfs2/ifile.c:73 nilfs_new_inode+0x254/0x830 fs/nilfs2/inode.c:344 nilfs_mkdir+0x10d/0x340 fs/nilfs2/namei.c:218 vfs_mkdir+0x2f9/0x4f0 fs/namei.c:4257 do_mkdirat+0x264/0x3a0 fs/namei.c:4280 __do_sys_mkdirat fs/namei.c:4295 [inline] __se_sys_mkdirat fs/namei.c:4293 [inline] __x64_sys_mkdirat+0x87/0xa0 fs/namei.c:4293 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f The other is when nilfs_btree_propagate(), which propagates the dirty state to the ancestor nodes of a b-tree that point to a dirty buffer, detects that the origin buffer is not dirty, even though it should be: WARNING: CPU: 0 PID: 5245 at fs/nilfs2/btree.c:2089 nilfs_btree_propagate+0xc79/0xdf0 fs/nilfs2/btree.c:2089 ... Call Trace: nilfs_bmap_propagate+0x75/0x120 fs/nilfs2/bmap.c:345 nilfs_collect_file_data+0x4d/0xd0 fs/nilfs2/segment.c:587 nilfs_segctor_apply_buffers+0x184/0x340 fs/nilfs2/segment.c:1006 nilfs_segctor_scan_file+0x28c/0xa50 fs/nilfs2/segment.c:1045 nilfs_segctor_collect_blocks fs/nilfs2/segment.c:1216 [inline] nilfs_segctor_collect fs/nilfs2/segment.c:1540 [inline] nilfs_segctor_do_construct+0x1c28/0x6b90 fs/nilfs2/segment.c:2115 nilfs_segctor_construct+0x181/0x6b0 fs/nilfs2/segment.c:2479 nilfs_segctor_thread_construct fs/nilfs2/segment.c:2587 [inline] nilfs_segctor_thread+0x69e/0xe80 fs/nilfs2/segment.c:2701 kthread+0x2f0/0x390 kernel/kthread.c:389 ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244 Both of these issues are caused by the callbacks that handle the page/folio write requests, forcibly clear various states, including the working state of the buffers they hold, at unexpected times when they detect read-only fallback. Fix these issues by checking if the buffer is referenced before clearing the page/folio state, and skipping the clear if it is. Link: https://lkml.kernel.org/r/20250107200202.6432-1-konishi.ryusuke@gmail.com Link: https://lkml.kernel.org/r/20250107200202.6432-2-konishi.ryusuke@gmail.com Signed-off-by: Ryusuke Konishi Reported-by: syzbot+b2b14916b77acf8626d7@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=b2b14916b77acf8626d7 Reported-by: syzbot+d98fd19acd08b36ff422@syzkaller.appspotmail.com Link: https://syzkaller.appspot.com/bug?extid=d98fd19acd08b36ff422 Fixes: 8c26c4e2694a ("nilfs2: fix issue with flush kernel thread after remount in RO mode because of driver's internal error or metadata corruption") Tested-by: syzbot+b2b14916b77acf8626d7@syzkaller.appspotmail.com Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin --- fs/nilfs2/page.c | 35 +++++++++++++++++++++++++++++------ 1 file changed, 29 insertions(+), 6 deletions(-) diff --git a/fs/nilfs2/page.c b/fs/nilfs2/page.c index dd40357d836b2..2dbf74936a7ed 100644 --- a/fs/nilfs2/page.c +++ b/fs/nilfs2/page.c @@ -405,6 +405,11 @@ void nilfs_clear_dirty_pages(struct address_space *mapping, bool silent) * nilfs_clear_dirty_page - discard dirty page * @page: dirty page that will be discarded * @silent: suppress [true] or print [false] warning messages + * + * nilfs_clear_dirty_page() clears working states including dirty state for + * the page and its buffers. If the page has buffers, clear only if it is + * confirmed that none of the buffer heads are busy (none have valid + * references and none are locked). */ void nilfs_clear_dirty_page(struct page *page, bool silent) { @@ -417,19 +422,34 @@ void nilfs_clear_dirty_page(struct page *page, bool silent) nilfs_warn(sb, "discard dirty page: offset=%lld, ino=%lu", page_offset(page), inode->i_ino); - ClearPageUptodate(page); - ClearPageMappedToDisk(page); - ClearPageChecked(page); - if (page_has_buffers(page)) { - struct buffer_head *bh, *head; + struct buffer_head *bh, *head = page_buffers(page); const unsigned long clear_bits = (BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) | BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) | BIT(BH_NILFS_Checked) | BIT(BH_NILFS_Redirected) | BIT(BH_Delay)); + bool busy, invalidated = false; + +recheck_buffers: + busy = false; + bh = head; + do { + if (atomic_read(&bh->b_count) | buffer_locked(bh)) { + busy = true; + break; + } + } while (bh = bh->b_this_page, bh != head); + + if (busy) { + if (invalidated) + return; + invalidate_bh_lrus(); + invalidated = true; + goto recheck_buffers; + } - bh = head = page_buffers(page); + bh = head; do { lock_buffer(bh); if (!silent) @@ -442,6 +462,9 @@ void nilfs_clear_dirty_page(struct page *page, bool silent) } while (bh = bh->b_this_page, bh != head); } + ClearPageUptodate(page); + ClearPageMappedToDisk(page); + ClearPageChecked(page); __nilfs_clear_page_dirty(page); } -- 2.53.0