5.3-stable patches

added patches:
	cgroup-writeback-don-t-switch-wbs-immediately-on-dead-wbs-if-the-memcg-is-dead.patch
	mm-filemap.c-don-t-initiate-writeback-if-mapping-has-no-dirty-pages.patch

diff --git a/queue-5.3/cgroup-writeback-don-t-switch-wbs-immediately-on-dead-wbs-if-the-memcg-is-dead.patch b/queue-5.3/cgroup-writeback-don-t-switch-wbs-immediately-on-dead-wbs-if-the-memcg-is-dead.patch
new file mode 100644 (file)
index 0000000..24feb1d
--- /dev/null
+++ b/queue-5.3/cgroup-writeback-don-t-switch-wbs-immediately-on-dead-wbs-if-the-memcg-is-dead.patch
@@ -0,0 +1,62 @@
+From 65de03e251382306a4575b1779c57c87889eee49 Mon Sep 17 00:00:00 2001
+From: Tejun Heo <tj@kernel.org>
+Date: Fri, 8 Nov 2019 12:18:29 -0800
+Subject: cgroup,writeback: don't switch wbs immediately on dead wbs if the memcg is dead
+
+From: Tejun Heo <tj@kernel.org>
+
+commit 65de03e251382306a4575b1779c57c87889eee49 upstream.
+
+cgroup writeback tries to refresh the associated wb immediately if the
+current wb is dead.  This is to avoid keeping issuing IOs on the stale
+wb after memcg - blkcg association has changed (ie. when blkcg got
+disabled / enabled higher up in the hierarchy).
+
+Unfortunately, the logic gets triggered spuriously on inodes which are
+associated with dead cgroups.  When the logic is triggered on dead
+cgroups, the attempt fails only after doing quite a bit of work
+allocating and initializing a new wb.
+
+While c3aab9a0bd91 ("mm/filemap.c: don't initiate writeback if mapping
+has no dirty pages") alleviated the issue significantly as it now only
+triggers when the inode has dirty pages.  However, the condition can
+still be triggered before the inode is switched to a different cgroup
+and the logic simply doesn't make sense.
+
+Skip the immediate switching if the associated memcg is dying.
+
+This is a simplified version of the following two patches:
+
+ * https://lore.kernel.org/linux-mm/20190513183053.GA73423@dennisz-mbp/
+ * http://lkml.kernel.org/r/156355839560.2063.5265687291430814589.stgit@buzz
+
+Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Fixes: e8a7abf5a5bd ("writeback: disassociate inodes from dying bdi_writebacks")
+Acked-by: Dennis Zhou <dennis@kernel.org>
+Signed-off-by: Tejun Heo <tj@kernel.org>
+Signed-off-by: Jens Axboe <axboe@kernel.dk>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ fs/fs-writeback.c |    9 ++++++---
+ 1 file changed, 6 insertions(+), 3 deletions(-)
+
+--- a/fs/fs-writeback.c
++++ b/fs/fs-writeback.c
+@@ -577,10 +577,13 @@ void wbc_attach_and_unlock_inode(struct
+       spin_unlock(&inode->i_lock);
+ 
+       /*
+-       * A dying wb indicates that the memcg-blkcg mapping has changed
+-       * and a new wb is already serving the memcg.  Switch immediately.
++       * A dying wb indicates that either the blkcg associated with the
++       * memcg changed or the associated memcg is dying.  In the first
++       * case, a replacement wb should already be available and we should
++       * refresh the wb immediately.  In the second case, trying to
++       * refresh will keep failing.
+        */
+-      if (unlikely(wb_dying(wbc->wb)))
++      if (unlikely(wb_dying(wbc->wb) && !css_is_dying(wbc->wb->memcg_css)))
+               inode_switch_wbs(inode, wbc->wb_id);
+ }
+ EXPORT_SYMBOL_GPL(wbc_attach_and_unlock_inode);

diff --git a/queue-5.3/mm-filemap.c-don-t-initiate-writeback-if-mapping-has-no-dirty-pages.patch b/queue-5.3/mm-filemap.c-don-t-initiate-writeback-if-mapping-has-no-dirty-pages.patch
new file mode 100644 (file)
index 0000000..f7b4d82
--- /dev/null
+++ b/queue-5.3/mm-filemap.c-don-t-initiate-writeback-if-mapping-has-no-dirty-pages.patch
@@ -0,0 +1,49 @@
+From c3aab9a0bd91b696a852169479b7db1ece6cbf8c Mon Sep 17 00:00:00 2001
+From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Date: Mon, 23 Sep 2019 15:34:45 -0700
+Subject: mm/filemap.c: don't initiate writeback if mapping has no dirty pages
+
+From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+
+commit c3aab9a0bd91b696a852169479b7db1ece6cbf8c upstream.
+
+Functions like filemap_write_and_wait_range() should do nothing if inode
+has no dirty pages or pages currently under writeback.  But they anyway
+construct struct writeback_control and this does some atomic operations if
+CONFIG_CGROUP_WRITEBACK=y - on fast path it locks inode->i_lock and
+updates state of writeback ownership, on slow path might be more work.
+Current this path is safely avoided only when inode mapping has no pages.
+
+For example generic_file_read_iter() calls filemap_write_and_wait_range()
+at each O_DIRECT read - pretty hot path.
+
+This patch skips starting new writeback if mapping has no dirty tags set.
+If writeback is already in progress filemap_write_and_wait_range() will
+wait for it.
+
+Link: http://lkml.kernel.org/r/156378816804.1087.8607636317907921438.stgit@buzz
+Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
+Reviewed-by: Jan Kara <jack@suse.cz>
+Cc: Tejun Heo <tj@kernel.org>
+Cc: Jens Axboe <axboe@kernel.dk>
+Cc: Johannes Weiner <hannes@cmpxchg.org>
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ mm/filemap.c |    3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+--- a/mm/filemap.c
++++ b/mm/filemap.c
+@@ -408,7 +408,8 @@ int __filemap_fdatawrite_range(struct ad
+               .range_end = end,
+       };
+ 
+-      if (!mapping_cap_writeback_dirty(mapping))
++      if (!mapping_cap_writeback_dirty(mapping) ||
++          !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
+               return 0;
+ 
+       wbc_attach_fdatawrite_inode(&wbc, mapping->host);

diff --git a/queue-5.3/series b/queue-5.3/series
index 3b96a12ca5064ac2c9d8e7d49329b3157b7adc78..074effee466962bf1dd0c848a4f991d3a3aaafac 100644 (file)
--- a/queue-5.3/series
+++ b/queue-5.3/series
@@ -189,3 +189,5 @@ ocfs2-protect-extent-tree-in-ocfs2_prepare_inode_for.patch
 pinctrl-cherryview-fix-irq_valid_mask-calculation.patch
 clk-imx8m-use-sys_pll1_800m-as-intermediate-parent-o.patch
 timekeeping-vsyscall-update-vdso-data-unconditionall.patch
+mm-filemap.c-don-t-initiate-writeback-if-mapping-has-no-dirty-pages.patch
+cgroup-writeback-don-t-switch-wbs-immediately-on-dead-wbs-if-the-memcg-is-dead.patch