5.4-stable patches

added patches:
	mm-memcg-fix-memcg-reclaim-soft-lockup.patch

diff --git a/queue-5.4/mm-memcg-fix-memcg-reclaim-soft-lockup.patch b/queue-5.4/mm-memcg-fix-memcg-reclaim-soft-lockup.patch
new file mode 100644 (file)
index 0000000..ad47efe
--- /dev/null
+++ b/queue-5.4/mm-memcg-fix-memcg-reclaim-soft-lockup.patch
@@ -0,0 +1,77 @@
+From e3336cab2579012b1e72b5265adf98e2d6e244ad Mon Sep 17 00:00:00 2001
+From: Xunlei Pang <xlpang@linux.alibaba.com>
+Date: Fri, 4 Sep 2020 16:35:27 -0700
+Subject: mm: memcg: fix memcg reclaim soft lockup
+
+From: Xunlei Pang <xlpang@linux.alibaba.com>
+
+commit e3336cab2579012b1e72b5265adf98e2d6e244ad upstream.
+
+We've met softlockup with "CONFIG_PREEMPT_NONE=y", when the target memcg
+doesn't have any reclaimable memory.
+
+It can be easily reproduced as below:
+
+  watchdog: BUG: soft lockup - CPU#0 stuck for 111s![memcg_test:2204]
+  CPU: 0 PID: 2204 Comm: memcg_test Not tainted 5.9.0-rc2+ #12
+  Call Trace:
+    shrink_lruvec+0x49f/0x640
+    shrink_node+0x2a6/0x6f0
+    do_try_to_free_pages+0xe9/0x3e0
+    try_to_free_mem_cgroup_pages+0xef/0x1f0
+    try_charge+0x2c1/0x750
+    mem_cgroup_charge+0xd7/0x240
+    __add_to_page_cache_locked+0x2fd/0x370
+    add_to_page_cache_lru+0x4a/0xc0
+    pagecache_get_page+0x10b/0x2f0
+    filemap_fault+0x661/0xad0
+    ext4_filemap_fault+0x2c/0x40
+    __do_fault+0x4d/0xf9
+    handle_mm_fault+0x1080/0x1790
+
+It only happens on our 1-vcpu instances, because there's no chance for
+oom reaper to run to reclaim the to-be-killed process.
+
+Add a cond_resched() at the upper shrink_node_memcgs() to solve this
+issue, this will mean that we will get a scheduling point for each memcg
+in the reclaimed hierarchy without any dependency on the reclaimable
+memory in that memcg thus making it more predictable.
+
+Suggested-by: Michal Hocko <mhocko@suse.com>
+Signed-off-by: Xunlei Pang <xlpang@linux.alibaba.com>
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Acked-by: Chris Down <chris@chrisdown.name>
+Acked-by: Michal Hocko <mhocko@suse.com>
+Acked-by: Johannes Weiner <hannes@cmpxchg.org>
+Link: http://lkml.kernel.org/r/1598495549-67324-1-git-send-email-xlpang@linux.alibaba.com
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Fixes: b0dedc49a2da ("mm/vmscan.c: iterate only over charged shrinkers during memcg shrink_slab()")
+Cc: stable@vger.kernel.org
+Signed-off-by: Julius Hemanth Pitti <jpitti@cisco.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ mm/vmscan.c | 8 ++++++++
+ 1 file changed, 8 insertions(+)
+
+diff --git a/mm/vmscan.c b/mm/vmscan.c
+index 749d239c62b2..8b97bc615d8c 100644
+--- a/mm/vmscan.c
++++ b/mm/vmscan.c
+@@ -2619,6 +2619,14 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)
+               unsigned long reclaimed;
+               unsigned long scanned;
+ 
++              /*
++               * This loop can become CPU-bound when target memcgs
++               * aren't eligible for reclaim - either because they
++               * don't have any reclaimable pages, or because their
++               * memory is explicitly protected. Avoid soft lockups.
++               */
++              cond_resched();
++
+               switch (mem_cgroup_protected(target_memcg, memcg)) {
+               case MEMCG_PROT_MIN:
+                       /*
+-- 
+2.17.1
+

diff --git a/queue-5.4/series b/queue-5.4/series
index c129ae5ff4acfdc60e645eedf02645a719f7ae7d..074bcbccb590d41fc96eeb81dadf5c89678eec82 100644 (file)
--- a/queue-5.4/series
+++ b/queue-5.4/series
@@ -70,3 +70,4 @@ dm-dax-fix-table-reference-counts.patch
 mm-memory_hotplug-drain-per-cpu-pages-again-during-memory-offline.patch
 dm-call-proper-helper-to-determine-dax-support.patch
 dax-fix-compilation-for-config_dax-config_fs_dax.patch
+mm-memcg-fix-memcg-reclaim-soft-lockup.patch