linux-kernel - [PATCH 5.17 101/114] writeback: Avoid skipping inode writeback

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20220516193628.376212768@linuxfoundation.org>
Date:   Mon, 16 May 2022 21:37:15 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Jan Kara <jack@...e.cz>,
        Christoph Hellwig <hch@....de>, Jing Xia <jing.xia@...soc.com>
Subject: [PATCH 5.17 101/114] writeback: Avoid skipping inode writeback

From: Jing Xia <jing.xia@...soc.com>

commit 846a3351ddfe4a86eede4bb26a205c3f38ef84d3 upstream.

We have run into an issue that a task gets stuck in
balance_dirty_pages_ratelimited() when perform I/O stress testing.
The reason we observed is that an I_DIRTY_PAGES inode with lots
of dirty pages is in b_dirty_time list and standard background
writeback cannot writeback the inode.
After studing the relevant code, the following scenario may lead
to the issue:

task1                                   task2
-----                                   -----
fuse_flush
 write_inode_now //in b_dirty_time
  writeback_single_inode
   __writeback_single_inode
                                 fuse_write_end
                                  filemap_dirty_folio
                                   __xa_set_mark:PAGECACHE_TAG_DIRTY
    lock inode->i_lock
    if mapping tagged PAGECACHE_TAG_DIRTY
    inode->i_state |= I_DIRTY_PAGES
    unlock inode->i_lock
                                   __mark_inode_dirty:I_DIRTY_PAGES
                                      lock inode->i_lock
                                      -was dirty,inode stays in
                                      -b_dirty_time
                                      unlock inode->i_lock

   if(!(inode->i_state & I_DIRTY_All))
      -not true,so nothing done

This patch moves the dirty inode to b_dirty list when the inode
currently is not queued in b_io or b_more_io list at the end of
writeback_single_inode.

Reviewed-by: Jan Kara <jack@...e.cz>
Reviewed-by: Christoph Hellwig <hch@....de>
CC: stable@...r.kernel.org
Fixes: 0ae45f63d4ef ("vfs: add support for a lazytime mount option")
Signed-off-by: Jing Xia <jing.xia@...soc.com>
Signed-off-by: Jan Kara <jack@...e.cz>
Link: https://lore.kernel.org/r/20220510023514.27399-1-jing.xia@unisoc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/fs-writeback.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/fs/fs-writeback.c
+++ b/fs/fs-writeback.c
@@ -1749,6 +1749,10 @@ static int writeback_single_inode(struct
 	 */
 	if (!(inode->i_state & I_DIRTY_ALL))
 		inode_cgwb_move_to_attached(inode, wb);
+	else if (!(inode->i_state & I_SYNC_QUEUED) &&
+		 (inode->i_state & I_DIRTY))
+		redirty_tail_locked(inode, wb);
+
 	spin_unlock(&wb->list_lock);
 	inode_sync_complete(inode);
 out: