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authorYosry Ahmed <yosryahmed@google.com>2022-07-14 09:49:18 +0300
committerakpm <akpm@linux-foundation.org>2022-07-30 04:07:15 +0300
commit73b73bac90d97400e29e585c678c4d0ebfd2680d (patch)
tree194f251b03e9e3ed42264f0a1f1302c2fbefec97 /mm/vmscan.c
parentc7e6f17b52e9486a9d997368819dfec032b550e2 (diff)
downloadlinux-73b73bac90d97400e29e585c678c4d0ebfd2680d.tar.xz
mm: vmpressure: don't count proactive reclaim in vmpressure
memory.reclaim is a cgroup v2 interface that allows users to proactively reclaim memory from a memcg, without real memory pressure. Reclaim operations invoke vmpressure, which is used: (a) To notify userspace of reclaim efficiency in cgroup v1, and (b) As a signal for a memcg being under memory pressure for networking (see mem_cgroup_under_socket_pressure()). For (a), vmpressure notifications in v1 are not affected by this change since memory.reclaim is a v2 feature. For (b), the effects of the vmpressure signal (according to Shakeel [1]) are as follows: 1. Reducing send and receive buffers of the current socket. 2. May drop packets on the rx path. 3. May throttle current thread on the tx path. Since proactive reclaim is invoked directly by userspace, not by memory pressure, it makes sense not to throttle networking. Hence, this change makes sure that proactive reclaim caused by memory.reclaim does not trigger vmpressure. [1] https://lore.kernel.org/lkml/CALvZod68WdrXEmBpOkadhB5GPYmCXaDZzXH=yyGOCAjFRn4NDQ@mail.gmail.com/ [yosryahmed@google.com: update documentation] Link: https://lkml.kernel.org/r/20220721173015.2643248-1-yosryahmed@google.com Link: https://lkml.kernel.org/r/20220714064918.2576464-1-yosryahmed@google.com Signed-off-by: Yosry Ahmed <yosryahmed@google.com> Acked-by: Shakeel Butt <shakeelb@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: David Rientjes <rientjes@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Muchun Song <songmuchun@bytedance.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: David Hildenbrand <david@redhat.com> Cc: Miaohe Lin <linmiaohe@huawei.com> Cc: NeilBrown <neilb@suse.de> Cc: Alistair Popple <apopple@nvidia.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Peter Xu <peterx@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/vmscan.c')
-rw-r--r--mm/vmscan.c27
1 files changed, 17 insertions, 10 deletions
diff --git a/mm/vmscan.c b/mm/vmscan.c
index fbb4108250ee..9e7d8db42918 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -101,6 +101,9 @@ struct scan_control {
/* Can pages be swapped as part of reclaim? */
unsigned int may_swap:1;
+ /* Proactive reclaim invoked by userspace through memory.reclaim */
+ unsigned int proactive:1;
+
/*
* Cgroup memory below memory.low is protected as long as we
* don't threaten to OOM. If any cgroup is reclaimed at
@@ -3180,9 +3183,10 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc)
sc->priority);
/* Record the group's reclaim efficiency */
- vmpressure(sc->gfp_mask, memcg, false,
- sc->nr_scanned - scanned,
- sc->nr_reclaimed - reclaimed);
+ if (!sc->proactive)
+ vmpressure(sc->gfp_mask, memcg, false,
+ sc->nr_scanned - scanned,
+ sc->nr_reclaimed - reclaimed);
} while ((memcg = mem_cgroup_iter(target_memcg, memcg, NULL)));
}
@@ -3305,9 +3309,10 @@ again:
}
/* Record the subtree's reclaim efficiency */
- vmpressure(sc->gfp_mask, sc->target_mem_cgroup, true,
- sc->nr_scanned - nr_scanned,
- sc->nr_reclaimed - nr_reclaimed);
+ if (!sc->proactive)
+ vmpressure(sc->gfp_mask, sc->target_mem_cgroup, true,
+ sc->nr_scanned - nr_scanned,
+ sc->nr_reclaimed - nr_reclaimed);
if (sc->nr_reclaimed - nr_reclaimed)
reclaimable = true;
@@ -3589,8 +3594,9 @@ retry:
__count_zid_vm_events(ALLOCSTALL, sc->reclaim_idx, 1);
do {
- vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup,
- sc->priority);
+ if (!sc->proactive)
+ vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup,
+ sc->priority);
sc->nr_scanned = 0;
shrink_zones(zonelist, sc);
@@ -3880,7 +3886,7 @@ unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,
unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
unsigned long nr_pages,
gfp_t gfp_mask,
- bool may_swap)
+ unsigned int reclaim_options)
{
unsigned long nr_reclaimed;
unsigned int noreclaim_flag;
@@ -3893,7 +3899,8 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
.priority = DEF_PRIORITY,
.may_writepage = !laptop_mode,
.may_unmap = 1,
- .may_swap = may_swap,
+ .may_swap = !!(reclaim_options & MEMCG_RECLAIM_MAY_SWAP),
+ .proactive = !!(reclaim_options & MEMCG_RECLAIM_PROACTIVE),
};
/*
* Traverse the ZONELIST_FALLBACK zonelist of the current node to put