From 73b73bac90d97400e29e585c678c4d0ebfd2680d Mon Sep 17 00:00:00 2001 From: Yosry Ahmed Date: Thu, 14 Jul 2022 06:49:18 +0000 Subject: 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 Acked-by: Shakeel Butt Acked-by: Michal Hocko Acked-by: David Rientjes Cc: Johannes Weiner Cc: Roman Gushchin Cc: Muchun Song Cc: Matthew Wilcox Cc: Vlastimil Babka Cc: David Hildenbrand Cc: Miaohe Lin Cc: NeilBrown Cc: Alistair Popple Cc: Suren Baghdasaryan Cc: Peter Xu Signed-off-by: Andrew Morton --- mm/memcontrol.c | 24 ++++++++++++++---------- 1 file changed, 14 insertions(+), 10 deletions(-) (limited to 'mm/memcontrol.c') diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 767f49a6b987..2b831cc48c7d 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2330,7 +2330,8 @@ static unsigned long reclaim_high(struct mem_cgroup *memcg, psi_memstall_enter(&pflags); nr_reclaimed += try_to_free_mem_cgroup_pages(memcg, nr_pages, - gfp_mask, true); + gfp_mask, + MEMCG_RECLAIM_MAY_SWAP); psi_memstall_leave(&pflags); } while ((memcg = parent_mem_cgroup(memcg)) && !mem_cgroup_is_root(memcg)); @@ -2575,7 +2576,7 @@ static int try_charge_memcg(struct mem_cgroup *memcg, gfp_t gfp_mask, struct page_counter *counter; unsigned long nr_reclaimed; bool passed_oom = false; - bool may_swap = true; + unsigned int reclaim_options = MEMCG_RECLAIM_MAY_SWAP; bool drained = false; bool raised_max_event = false; unsigned long pflags; @@ -2593,7 +2594,7 @@ retry: mem_over_limit = mem_cgroup_from_counter(counter, memory); } else { mem_over_limit = mem_cgroup_from_counter(counter, memsw); - may_swap = false; + reclaim_options &= ~MEMCG_RECLAIM_MAY_SWAP; } if (batch > nr_pages) { @@ -2621,7 +2622,7 @@ retry: psi_memstall_enter(&pflags); nr_reclaimed = try_to_free_mem_cgroup_pages(mem_over_limit, nr_pages, - gfp_mask, may_swap); + gfp_mask, reclaim_options); psi_memstall_leave(&pflags); if (mem_cgroup_margin(mem_over_limit) >= nr_pages) @@ -3439,8 +3440,8 @@ static int mem_cgroup_resize_max(struct mem_cgroup *memcg, continue; } - if (!try_to_free_mem_cgroup_pages(memcg, 1, - GFP_KERNEL, !memsw)) { + if (!try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL, + memsw ? 0 : MEMCG_RECLAIM_MAY_SWAP)) { ret = -EBUSY; break; } @@ -3550,7 +3551,8 @@ static int mem_cgroup_force_empty(struct mem_cgroup *memcg) if (signal_pending(current)) return -EINTR; - if (!try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL, true)) + if (!try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL, + MEMCG_RECLAIM_MAY_SWAP)) nr_retries--; } @@ -6302,7 +6304,7 @@ static ssize_t memory_high_write(struct kernfs_open_file *of, } reclaimed = try_to_free_mem_cgroup_pages(memcg, nr_pages - high, - GFP_KERNEL, true); + GFP_KERNEL, MEMCG_RECLAIM_MAY_SWAP); if (!reclaimed && !nr_retries--) break; @@ -6351,7 +6353,7 @@ static ssize_t memory_max_write(struct kernfs_open_file *of, if (nr_reclaims) { if (!try_to_free_mem_cgroup_pages(memcg, nr_pages - max, - GFP_KERNEL, true)) + GFP_KERNEL, MEMCG_RECLAIM_MAY_SWAP)) nr_reclaims--; continue; } @@ -6480,6 +6482,7 @@ static ssize_t memory_reclaim(struct kernfs_open_file *of, char *buf, struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); unsigned int nr_retries = MAX_RECLAIM_RETRIES; unsigned long nr_to_reclaim, nr_reclaimed = 0; + unsigned int reclaim_options; int err; buf = strstrip(buf); @@ -6487,6 +6490,7 @@ static ssize_t memory_reclaim(struct kernfs_open_file *of, char *buf, if (err) return err; + reclaim_options = MEMCG_RECLAIM_MAY_SWAP | MEMCG_RECLAIM_PROACTIVE; while (nr_reclaimed < nr_to_reclaim) { unsigned long reclaimed; @@ -6503,7 +6507,7 @@ static ssize_t memory_reclaim(struct kernfs_open_file *of, char *buf, reclaimed = try_to_free_mem_cgroup_pages(memcg, nr_to_reclaim - nr_reclaimed, - GFP_KERNEL, true); + GFP_KERNEL, reclaim_options); if (!reclaimed && !nr_retries--) return -EAGAIN; -- cgit v1.2.3