4.9-stable patches

added patches:
	fs-writeback-writeback_sb_inodes-recalculate-wrote-according-skipped-pages.patch

diff --git a/queue-4.9/fs-writeback-writeback_sb_inodes-recalculate-wrote-according-skipped-pages.patch b/queue-4.9/fs-writeback-writeback_sb_inodes-recalculate-wrote-according-skipped-pages.patch
new file mode 100644 (file)
index 0000000..23fd830
--- /dev/null
+++ b/queue-4.9/fs-writeback-writeback_sb_inodes-recalculate-wrote-according-skipped-pages.patch
@@ -0,0 +1,154 @@
+From 68f4c6eba70df70a720188bce95c85570ddfcc87 Mon Sep 17 00:00:00 2001
+From: Zhihao Cheng <chengzhihao1@huawei.com>
+Date: Tue, 10 May 2022 21:38:05 +0800
+Subject: fs-writeback: writeback_sb_inodes：Recalculate 'wrote' according skipped pages
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+From: Zhihao Cheng <chengzhihao1@huawei.com>
+
+commit 68f4c6eba70df70a720188bce95c85570ddfcc87 upstream.
+
+Commit 505a666ee3fc ("writeback: plug writeback in wb_writeback() and
+writeback_inodes_wb()") has us holding a plug during wb_writeback, which
+may cause a potential ABBA dead lock:
+
+    wb_writeback               fat_file_fsync
+blk_start_plug(&plug)
+for (;;) {
+  iter i-1: some reqs have been added into plug->mq_list  // LOCK A
+  iter i:
+    progress = __writeback_inodes_wb(wb, work)
+    . writeback_sb_inodes // fat's bdev
+    .   __writeback_single_inode
+    .   . generic_writepages
+    .   .   __block_write_full_page
+    .   .   . .            __generic_file_fsync
+    .   .   . .              sync_inode_metadata
+    .   .   . .                writeback_single_inode
+    .   .   . .                  __writeback_single_inode
+    .   .   . .                    fat_write_inode
+    .   .   . .                      __fat_write_inode
+    .   .   . .                        sync_dirty_buffer       // fat's bdev
+    .   .   . .                          lock_buffer(bh)       // LOCK B
+    .   .   . .                            submit_bh
+    .   .   . .                              blk_mq_get_tag    // LOCK A
+    .   .   . trylock_buffer(bh)  // LOCK B
+    .   .   .   redirty_page_for_writepage
+    .   .   .     wbc->pages_skipped++
+    .   .   --wbc->nr_to_write
+    .   wrote += write_chunk - wbc.nr_to_write  // wrote > 0
+    .   requeue_inode
+    .     redirty_tail_locked
+    if (progress)    // progress > 0
+      continue;
+  iter i+1:
+      queue_io
+      // similar process with iter i, infinite for-loop !
+}
+blk_finish_plug(&plug)   // flush plug won't be called
+
+Above process triggers a hungtask like:
+[  399.044861] INFO: task bb:2607 blocked for more than 30 seconds.
+[  399.046824]       Not tainted 5.18.0-rc1-00005-gefae4d9eb6a2-dirty
+[  399.051539] task:bb              state:D stack:    0 pid: 2607 ppid:
+2426 flags:0x00004000
+[  399.051556] Call Trace:
+[  399.051570]  __schedule+0x480/0x1050
+[  399.051592]  schedule+0x92/0x1a0
+[  399.051602]  io_schedule+0x22/0x50
+[  399.051613]  blk_mq_get_tag+0x1d3/0x3c0
+[  399.051640]  __blk_mq_alloc_requests+0x21d/0x3f0
+[  399.051657]  blk_mq_submit_bio+0x68d/0xca0
+[  399.051674]  __submit_bio+0x1b5/0x2d0
+[  399.051708]  submit_bio_noacct+0x34e/0x720
+[  399.051718]  submit_bio+0x3b/0x150
+[  399.051725]  submit_bh_wbc+0x161/0x230
+[  399.051734]  __sync_dirty_buffer+0xd1/0x420
+[  399.051744]  sync_dirty_buffer+0x17/0x20
+[  399.051750]  __fat_write_inode+0x289/0x310
+[  399.051766]  fat_write_inode+0x2a/0xa0
+[  399.051783]  __writeback_single_inode+0x53c/0x6f0
+[  399.051795]  writeback_single_inode+0x145/0x200
+[  399.051803]  sync_inode_metadata+0x45/0x70
+[  399.051856]  __generic_file_fsync+0xa3/0x150
+[  399.051880]  fat_file_fsync+0x1d/0x80
+[  399.051895]  vfs_fsync_range+0x40/0xb0
+[  399.051929]  __x64_sys_fsync+0x18/0x30
+
+In my test, 'need_resched()' (which is imported by 590dca3a71 "fs-writeback:
+unplug before cond_resched in writeback_sb_inodes") in function
+'writeback_sb_inodes()' seldom comes true, unless cond_resched() is deleted
+from write_cache_pages().
+
+Fix it by correcting wrote number according number of skipped pages
+in writeback_sb_inodes().
+
+Goto Link to find a reproducer.
+
+Link: https://bugzilla.kernel.org/show_bug.cgi?id=215837
+Cc: stable@vger.kernel.org # v4.3
+Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
+Reviewed-by: Jan Kara <jack@suse.cz>
+Reviewed-by: Christoph Hellwig <hch@lst.de>
+Link: https://lore.kernel.org/r/20220510133805.1988292-1-chengzhihao1@huawei.com
+Signed-off-by: Jens Axboe <axboe@kernel.dk>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ fs/fs-writeback.c |   13 ++++++++-----
+ 1 file changed, 8 insertions(+), 5 deletions(-)
+
+--- a/fs/fs-writeback.c
++++ b/fs/fs-writeback.c
+@@ -1569,11 +1569,12 @@ static long writeback_sb_inodes(struct s
+       };
+       unsigned long start_time = jiffies;
+       long write_chunk;
+-      long wrote = 0;  /* count both pages and inodes */
++      long total_wrote = 0;  /* count both pages and inodes */
+ 
+       while (!list_empty(&wb->b_io)) {
+               struct inode *inode = wb_inode(wb->b_io.prev);
+               struct bdi_writeback *tmp_wb;
++              long wrote;
+ 
+               if (inode->i_sb != sb) {
+                       if (work->sb) {
+@@ -1649,7 +1650,9 @@ static long writeback_sb_inodes(struct s
+ 
+               wbc_detach_inode(&wbc);
+               work->nr_pages -= write_chunk - wbc.nr_to_write;
+-              wrote += write_chunk - wbc.nr_to_write;
++              wrote = write_chunk - wbc.nr_to_write - wbc.pages_skipped;
++              wrote = wrote < 0 ? 0 : wrote;
++              total_wrote += wrote;
+ 
+               if (need_resched()) {
+                       /*
+@@ -1671,7 +1674,7 @@ static long writeback_sb_inodes(struct s
+               tmp_wb = inode_to_wb_and_lock_list(inode);
+               spin_lock(&inode->i_lock);
+               if (!(inode->i_state & I_DIRTY_ALL))
+-                      wrote++;
++                      total_wrote++;
+               requeue_inode(inode, tmp_wb, &wbc);
+               inode_sync_complete(inode);
+               spin_unlock(&inode->i_lock);
+@@ -1685,14 +1688,14 @@ static long writeback_sb_inodes(struct s
+                * bail out to wb_writeback() often enough to check
+                * background threshold and other termination conditions.
+                */
+-              if (wrote) {
++              if (total_wrote) {
+                       if (time_is_before_jiffies(start_time + HZ / 10UL))
+                               break;
+                       if (work->nr_pages <= 0)
+                               break;
+               }
+       }
+-      return wrote;
++      return total_wrote;
+ }
+ 
+ static long __writeback_inodes_wb(struct bdi_writeback *wb,

diff --git a/queue-4.9/series b/queue-4.9/series
index 8cd362258df777f6bbc915df4b426e178cf03d57..e329aaf7a5463e49ffdd072e19bb62b843fb9a15 100644 (file)
--- a/queue-4.9/series
+++ b/queue-4.9/series
@@ -75,3 +75,4 @@ video-fbdev-clcdfb-fix-refcount-leak-in-clcdfb_of_vr.patch
 iommu-amd-increase-timeout-waiting-for-ga-log-enable.patch
 wifi-mac80211-fix-use-after-free-in-chanctx-code.patch
 iwlwifi-mvm-fix-assert-1f04-upon-reconfig.patch
+fs-writeback-writeback_sb_inodes-recalculate-wrote-according-skipped-pages.patch