Subject: + memcg-do-not-replicate-get_mem_cgroup_from_mm-in-__mem_cgroup_try_charge.patch added to -mm tree
To: mhocko@xxxxxxx,hannes@xxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Wed, 12 Mar 2014 14:04:02 -0700
The patch titled
Subject: memcg: do not replicate get_mem_cgroup_from_mm in __mem_cgroup_try_charge
has been added to the -mm tree. Its filename is
memcg-do-not-replicate-get_mem_cgroup_from_mm-in-__mem_cgroup_try_charge.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/memcg-do-not-replicate-get_mem_cgroup_from_mm-in-__mem_cgroup_try_charge.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/memcg-do-not-replicate-get_mem_cgroup_from_mm-in-__mem_cgroup_try_charge.patch
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------------------------------------------------------
From: Michal Hocko <mhocko@xxxxxxx>
Subject: memcg: do not replicate get_mem_cgroup_from_mm in __mem_cgroup_try_charge
__mem_cgroup_try_charge duplicates get_mem_cgroup_from_mm for charges
which came without a memcg. The only reason seems to be a tiny
optimization when css_tryget is not called if the charge can be consumed
from the stock. Nevertheless css_tryget is very cheap since it has been
reworked to use per-cpu counting so this optimization doesn't give us
anything these days.
So let's drop the code duplication so that the code is more readable.
Signed-off-by: Michal Hocko <mhocko@xxxxxxx>
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 50 +++++-----------------------------------------
1 file changed, 6 insertions(+), 44 deletions(-)
diff -puN mm/memcontrol.c~memcg-do-not-replicate-get_mem_cgroup_from_mm-in-__mem_cgroup_try_charge mm/memcontrol.c
--- a/mm/memcontrol.c~memcg-do-not-replicate-get_mem_cgroup_from_mm-in-__mem_cgroup_try_charge
+++ a/mm/memcontrol.c
@@ -2731,52 +2731,14 @@ static int __mem_cgroup_try_charge(struc
again:
if (*ptr) { /* css should be a valid one */
memcg = *ptr;
- if (mem_cgroup_is_root(memcg))
- goto done;
- if (consume_stock(memcg, nr_pages))
- goto done;
css_get(&memcg->css);
} else {
- struct task_struct *p;
-
- rcu_read_lock();
- p = rcu_dereference(mm->owner);
- /*
- * Because we don't have task_lock(), "p" can exit.
- * In that case, "memcg" can point to root or p can be NULL with
- * race with swapoff. Then, we have small risk of mis-accouning.
- * But such kind of mis-account by race always happens because
- * we don't have cgroup_mutex(). It's overkill and we allo that
- * small race, here.
- * (*) swapoff at el will charge against mm-struct not against
- * task-struct. So, mm->owner can be NULL.
- */
- memcg = mem_cgroup_from_task(p);
- if (!memcg)
- memcg = root_mem_cgroup;
- if (mem_cgroup_is_root(memcg)) {
- rcu_read_unlock();
- goto done;
- }
- if (consume_stock(memcg, nr_pages)) {
- /*
- * It seems dagerous to access memcg without css_get().
- * But considering how consume_stok works, it's not
- * necessary. If consume_stock success, some charges
- * from this memcg are cached on this cpu. So, we
- * don't need to call css_get()/css_tryget() before
- * calling consume_stock().
- */
- rcu_read_unlock();
- goto done;
- }
- /* after here, we may be blocked. we need to get refcnt */
- if (!css_tryget(&memcg->css)) {
- rcu_read_unlock();
- goto again;
- }
- rcu_read_unlock();
+ memcg = get_mem_cgroup_from_mm(mm);
}
+ if (mem_cgroup_is_root(memcg))
+ goto done;
+ if (consume_stock(memcg, nr_pages))
+ goto done;
do {
bool invoke_oom = oom && !nr_oom_retries;
@@ -2812,8 +2774,8 @@ again:
if (batch > nr_pages)
refill_stock(memcg, batch - nr_pages);
- css_put(&memcg->css);
done:
+ css_put(&memcg->css);
*ptr = memcg;
return 0;
nomem:
_
Patches currently in -mm which might be from mhocko@xxxxxxx are
mm-vmscan-respect-numa-policy-mask-when-shrinking-slab-on-direct-reclaim.patch
mm-vmscan-move-call-to-shrink_slab-to-shrink_zones.patch
mm-vmscan-remove-shrink_control-arg-from-do_try_to_free_pages.patch
mm-hugetlb-mark-some-bootstrap-functions-as-__init.patch
pagewalk-update-page-table-walker-core.patch
pagewalk-add-walk_page_vma.patch
smaps-redefine-callback-functions-for-page-table-walker.patch
clear_refs-redefine-callback-functions-for-page-table-walker.patch
pagemap-redefine-callback-functions-for-page-table-walker.patch
numa_maps-redefine-callback-functions-for-page-table-walker.patch
memcg-redefine-callback-functions-for-page-table-walker.patch
madvise-redefine-callback-functions-for-page-table-walker.patch
arch-powerpc-mm-subpage-protc-use-walk_page_vma-instead-of-walk_page_range.patch
pagewalk-remove-argument-hmask-from-hugetlb_entry.patch
mempolicy-apply-page-table-walker-on-queue_pages_range.patch
drop_caches-add-some-documentation-and-info-message.patch
mm-exclude-memory-less-nodes-from-zone_reclaim.patch
fork-collapse-copy_flags-into-copy_process.patch
mm-mempolicy-rename-slab_node-for-clarity.patch
mm-mempolicy-remove-per-process-flag.patch
res_counter-remove-interface-for-locked-charging-and-uncharging.patch
mm-memcg-remove-unnecessary-preemption-disabling.patch
mm-memcg-remove-mem_cgroup_move_account_page_stat.patch
mm-memcg-inline-mem_cgroup_charge_common.patch
mm-memcg-push-mm-handling-out-to-page-cache-charge-function.patch
memcg-remove-unnecessary-mm-check-from-try_get_mem_cgroup_from_mm.patch
memcg-get_mem_cgroup_from_mm.patch
memcg-do-not-replicate-get_mem_cgroup_from_mm-in-__mem_cgroup_try_charge.patch
memcg-sanitize-__mem_cgroup_try_charge-call-protocol.patch
memcg-sanitize-__mem_cgroup_try_charge-call-protocol-fix.patch
memcg-rename-high-level-charging-functions.patch
printk-remove-duplicated-check-for-log-level.patch
printk-remove-obsolete-check-for-log-level-c.patch
printk-add-comment-about-tricky-check-for-text-buffer-size.patch
printk-use-also-the-last-bytes-in-the-ring-buffer.patch
printk-do-not-compute-the-size-of-the-message-twice.patch
linux-next.patch
memcg-slab-never-try-to-merge-memcg-caches.patch
memcg-slab-cleanup-memcg-cache-creation.patch
memcg-slab-separate-memcg-vs-root-cache-creation-paths.patch
memcg-slab-unregister-cache-from-memcg-before-starting-to-destroy-it.patch
memcg-slab-do-not-destroy-children-caches-if-parent-has-aliases.patch
slub-adjust-memcg-caches-when-creating-cache-alias.patch
slub-rework-sysfs-layout-for-memcg-caches.patch
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