Commit bc8e51c0 authored by Shakeel Butt's avatar Shakeel Butt Committed by Andrew Morton
Browse files

mm: memcg: dump memcg protection info on oom or alloc failures 

Currently kernel dumps memory state on oom and allocation failures.  One
of the question usually raised on those dumps is why the kernel has not
reclaimed the reclaimable memory instead of triggering oom.  One potential
reason is the usage of memory protection provided by memcg.  So, let's
also dump the memory protected by the memcg in such reports to ease the
debugging.

Link: https://lkml.kernel.org/r/20251107234041.3632644-1-shakeel.butt@linux.dev


Signed-off-by: default avatarShakeel Butt <shakeel.butt@linux.dev>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 05be0287

include/linux/memcontrol.h

+5 −0
Original line number Diff line number Diff line
@@ -1764,6 +1764,7 @@ static inline void count_objcg_events(struct obj_cgroup *objcg, 


bool mem_cgroup_node_allowed(struct mem_cgroup *memcg, int nid);



void mem_cgroup_show_protected_memory(struct mem_cgroup *memcg);

#else

static inline bool mem_cgroup_kmem_disabled(void)

{
@@ -1830,6 +1831,10 @@ static inline bool mem_cgroup_node_allowed(struct mem_cgroup *memcg, int nid) 
{

	return true;

}



static inline void mem_cgroup_show_protected_memory(struct mem_cgroup *memcg)

{

}

#endif /* CONFIG_MEMCG */



#if defined(CONFIG_MEMCG) && defined(CONFIG_ZSWAP)

mm/memcontrol.c

+13 −0
Original line number Diff line number Diff line
@@ -5635,3 +5635,16 @@ bool mem_cgroup_node_allowed(struct mem_cgroup *memcg, int nid) 
{

	return memcg ? cpuset_node_allowed(memcg->css.cgroup, nid) : true;

}



void mem_cgroup_show_protected_memory(struct mem_cgroup *memcg)

{

	if (mem_cgroup_disabled() || !cgroup_subsys_on_dfl(memory_cgrp_subsys))

		return;



	if (!memcg)

		memcg = root_mem_cgroup;



	pr_warn("Memory cgroup min protection %lukB -- low protection %lukB",

		K(atomic_long_read(&memcg->memory.children_min_usage)*PAGE_SIZE),

		K(atomic_long_read(&memcg->memory.children_low_usage)*PAGE_SIZE));

}

mm/oom_kill.c

+1 −0
Original line number Diff line number Diff line
@@ -472,6 +472,7 @@ static void dump_header(struct oom_control *oc) 
		if (should_dump_unreclaim_slab())

			dump_unreclaimable_slab();

	}

	mem_cgroup_show_protected_memory(oc->memcg);

	if (sysctl_oom_dump_tasks)

		dump_tasks(oc);

}

mm/page_alloc.c

+1 −0
Original line number Diff line number Diff line
@@ -3977,6 +3977,7 @@ static void warn_alloc_show_mem(gfp_t gfp_mask, nodemask_t *nodemask) 
		filter &= ~SHOW_MEM_FILTER_NODES;



	__show_mem(filter, nodemask, gfp_zone(gfp_mask));

	mem_cgroup_show_protected_memory(NULL);

}



void warn_alloc(gfp_t gfp_mask, nodemask_t *nodemask, const char *fmt, ...)