Revision 4e54dede38b45052a941bcf709f7d29f2e18174d authored by Michal Hocko on 27 February 2015, 23:51:46 UTC, committed by Linus Torvalds on 28 February 2015, 17:57:51 UTC
A memcg is considered low limited even when the current usage is equal to the low limit. This leads to interesting side effects e.g. groups/hierarchies with no memory accounted are considered protected and so the reclaim will emit MEMCG_LOW event when encountering them. Another and much bigger issue was reported by Joonsoo Kim. He has hit a NULL ptr dereference with the legacy cgroup API which even doesn't have low limit exposed. The limit is 0 by default but the initial check fails for memcg with 0 consumption and parent_mem_cgroup() would return NULL if use_hierarchy is 0 and so page_counter_read would try to dereference NULL. I suppose that the current implementation is just an overlook because the documentation in Documentation/cgroups/unified-hierarchy.txt says: "The memory.low boundary on the other hand is a top-down allocated reserve. A cgroup enjoys reclaim protection when it and all its ancestors are below their low boundaries" Fix the usage and the low limit comparision in mem_cgroup_low accordingly. Fixes: 241994ed8649 (mm: memcontrol: default hierarchy interface for memory) Reported-by: Joonsoo Kim <js1304@gmail.com> Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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File | Mode | Size |
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bpf | ||
configs | ||
debug | ||
events | ||
gcov | ||
irq | ||
livepatch | ||
locking | ||
power | ||
printk | ||
rcu | ||
sched | ||
time | ||
trace | ||
.gitignore | -rw-r--r-- | 91 bytes |
Kconfig.freezer | -rw-r--r-- | 52 bytes |
Kconfig.hz | -rw-r--r-- | 1.6 KB |
Kconfig.locks | -rw-r--r-- | 4.7 KB |
Kconfig.preempt | -rw-r--r-- | 2.1 KB |
Makefile | -rw-r--r-- | 7.3 KB |
acct.c | -rw-r--r-- | 15.4 KB |
async.c | -rw-r--r-- | 9.9 KB |
audit.c | -rw-r--r-- | 52.5 KB |
audit.h | -rw-r--r-- | 9.9 KB |
audit_tree.c | -rw-r--r-- | 22.0 KB |
audit_watch.c | -rw-r--r-- | 13.6 KB |
auditfilter.c | -rw-r--r-- | 33.7 KB |
auditsc.c | -rw-r--r-- | 64.2 KB |
backtracetest.c | -rw-r--r-- | 2.1 KB |
bounds.c | -rw-r--r-- | 703 bytes |
capability.c | -rw-r--r-- | 12.0 KB |
cgroup.c | -rw-r--r-- | 150.0 KB |
cgroup_freezer.c | -rw-r--r-- | 12.5 KB |
compat.c | -rw-r--r-- | 29.4 KB |
configs.c | -rw-r--r-- | 2.8 KB |
context_tracking.c | -rw-r--r-- | 5.7 KB |
cpu.c | -rw-r--r-- | 19.2 KB |
cpu_pm.c | -rw-r--r-- | 6.5 KB |
cpuset.c | -rw-r--r-- | 75.2 KB |
crash_dump.c | -rw-r--r-- | 1.3 KB |
cred.c | -rw-r--r-- | 21.2 KB |
delayacct.c | -rw-r--r-- | 4.5 KB |
dma.c | -rw-r--r-- | 3.6 KB |
elfcore.c | -rw-r--r-- | 396 bytes |
exec_domain.c | -rw-r--r-- | 4.3 KB |
exit.c | -rw-r--r-- | 41.5 KB |
extable.c | -rw-r--r-- | 4.0 KB |
fork.c | -rw-r--r-- | 47.9 KB |
freezer.c | -rw-r--r-- | 4.4 KB |
futex.c | -rw-r--r-- | 81.6 KB |
futex_compat.c | -rw-r--r-- | 4.5 KB |
groups.c | -rw-r--r-- | 6.0 KB |
hung_task.c | -rw-r--r-- | 5.7 KB |
irq_work.c | -rw-r--r-- | 4.5 KB |
jump_label.c | -rw-r--r-- | 11.0 KB |
kallsyms.c | -rw-r--r-- | 14.9 KB |
kcmp.c | -rw-r--r-- | 4.3 KB |
kexec.c | -rw-r--r-- | 67.7 KB |
kmod.c | -rw-r--r-- | 18.5 KB |
kprobes.c | -rw-r--r-- | 60.7 KB |
ksysfs.c | -rw-r--r-- | 5.6 KB |
kthread.c | -rw-r--r-- | 18.6 KB |
latencytop.c | -rw-r--r-- | 7.6 KB |
module-internal.h | -rw-r--r-- | 458 bytes |
module.c | -rw-r--r-- | 97.9 KB |
module_signing.c | -rw-r--r-- | 5.9 KB |
notifier.c | -rw-r--r-- | 16.2 KB |
nsproxy.c | -rw-r--r-- | 6.0 KB |
padata.c | -rw-r--r-- | 26.8 KB |
panic.c | -rw-r--r-- | 12.5 KB |
params.c | -rw-r--r-- | 22.6 KB |
pid.c | -rw-r--r-- | 14.9 KB |
pid_namespace.c | -rw-r--r-- | 10.0 KB |
profile.c | -rw-r--r-- | 16.1 KB |
ptrace.c | -rw-r--r-- | 29.4 KB |
range.c | -rw-r--r-- | 3.0 KB |
reboot.c | -rw-r--r-- | 12.5 KB |
relay.c | -rw-r--r-- | 32.6 KB |
resource.c | -rw-r--r-- | 37.2 KB |
seccomp.c | -rw-r--r-- | 24.0 KB |
signal.c | -rw-r--r-- | 95.4 KB |
smp.c | -rw-r--r-- | 19.4 KB |
smpboot.c | -rw-r--r-- | 7.0 KB |
smpboot.h | -rw-r--r-- | 564 bytes |
softirq.c | -rw-r--r-- | 18.9 KB |
stacktrace.c | -rw-r--r-- | 1.7 KB |
stop_machine.c | -rw-r--r-- | 17.2 KB |
sys.c | -rw-r--r-- | 56.5 KB |
sys_ni.c | -rw-r--r-- | 6.5 KB |
sysctl.c | -rw-r--r-- | 62.6 KB |
sysctl_binary.c | -rw-r--r-- | 51.0 KB |
system_certificates.S | -rw-r--r-- | 470 bytes |
system_keyring.c | -rw-r--r-- | 2.8 KB |
task_work.c | -rw-r--r-- | 3.4 KB |
taskstats.c | -rw-r--r-- | 16.1 KB |
test_kprobes.c | -rw-r--r-- | 7.4 KB |
torture.c | -rw-r--r-- | 19.9 KB |
tracepoint.c | -rw-r--r-- | 13.3 KB |
tsacct.c | -rw-r--r-- | 4.9 KB |
uid16.c | -rw-r--r-- | 5.0 KB |
up.c | -rw-r--r-- | 1.7 KB |
user-return-notifier.c | -rw-r--r-- | 1.3 KB |
user.c | -rw-r--r-- | 5.4 KB |
user_namespace.c | -rw-r--r-- | 25.5 KB |
utsname.c | -rw-r--r-- | 3.0 KB |
utsname_sysctl.c | -rw-r--r-- | 3.0 KB |
watchdog.c | -rw-r--r-- | 18.9 KB |
workqueue.c | -rw-r--r-- | 135.8 KB |
workqueue_internal.h | -rw-r--r-- | 2.2 KB |
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