Tejun Heo c3df5fb57f cgroup: rstat: fix A-A deadlock on 32bit around u64_stats_sync ... 0fa294fb19 ("cgroup: Replace cgroup_rstat_mutex with a spinlock") added cgroup_rstat_flush_irqsafe() allowing flushing to happen from the irq context. However, rstat paths use u64_stats_sync to synchronize access to 64bit stat counters on 32bit machines. u64_stats_sync is implemented using seq_lock and trying to read from an irq context can lead to A-A deadlock if the irq happens to interrupt the stat update. Fix it by using the irqsafe variants - u64_stats_update_begin_irqsave() and u64_stats_update_end_irqrestore() - in the update paths. Note that none of this matters on 64bit machines. All these are just for 32bit SMP setups. Note that the interface was introduced way back, its first and currently only use was recently added by 2d146aa3aa ("mm: memcontrol: switch to rstat"). Stable tagging targets this commit. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Rik van Riel <riel@surriel.com> Fixes: 2d146aa3aa ("mm: memcontrol: switch to rstat") Cc: stable@vger.kernel.org # v5.13+		2021-07-27 13:12:20 -10:00
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cgroup-internal.h
cgroup-v1.c	cgroup1: fix leaked context root causing sporadic NULL deref in LTP	2021-07-21 06:39:20 -10:00
cgroup.c	SCSI misc on 20210702	2021-07-02 15:14:36 -07:00
cpuset.c
debug.c
freezer.c
legacy_freezer.c
Makefile
misc.c
namespace.c
pids.c
rdma.c
rstat.c	cgroup: rstat: fix A-A deadlock on 32bit around u64_stats_sync	2021-07-27 13:12:20 -10:00