lkml.org 
[lkml]   [2020]   [Mar]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
Subject[PATCH 1/6] mm, memcg: Prevent memory.high load/store tearing
A mem_cgroup's high attribute can be concurrently set at the same time
as we are trying to read it -- for example, if we are in
memory_high_write at the same time as we are trying to do high reclaim.

Signed-off-by: Chris Down <chris@chrisdown.name>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Roman Gushchin <guro@fb.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: linux-mm@kvack.org
Cc: cgroups@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Cc: kernel-team@fb.com
---
mm/memcontrol.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 63bb6a2aab81..d32d3c0a16d4 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2228,7 +2228,7 @@ static void reclaim_high(struct mem_cgroup *memcg,
gfp_t gfp_mask)
{
do {
- if (page_counter_read(&memcg->memory) <= memcg->high)
+ if (page_counter_read(&memcg->memory) <= READ_ONCE(memcg->high))
continue;
memcg_memory_event(memcg, MEMCG_HIGH);
try_to_free_mem_cgroup_pages(memcg, nr_pages, gfp_mask, true);
@@ -2545,7 +2545,7 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask,
* reclaim, the cost of mismatch is negligible.
*/
do {
- if (page_counter_read(&memcg->memory) > memcg->high) {
+ if (page_counter_read(&memcg->memory) > READ_ONCE(memcg->high)) {
/* Don't bother a random interrupted task */
if (in_interrupt()) {
schedule_work(&memcg->high_work);
@@ -4257,7 +4257,8 @@ void mem_cgroup_wb_stats(struct bdi_writeback *wb, unsigned long *pfilepages,
*pheadroom = PAGE_COUNTER_MAX;

while ((parent = parent_mem_cgroup(memcg))) {
- unsigned long ceiling = min(memcg->memory.max, memcg->high);
+ unsigned long ceiling = min(memcg->memory.max,
+ READ_ONCE(memcg->high));
unsigned long used = page_counter_read(&memcg->memory);

*pheadroom = min(*pheadroom, ceiling - min(ceiling, used));
@@ -4978,7 +4979,7 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
if (!memcg)
return ERR_PTR(error);

- memcg->high = PAGE_COUNTER_MAX;
+ WRITE_ONCE(memcg->high, PAGE_COUNTER_MAX);
memcg->soft_limit = PAGE_COUNTER_MAX;
if (parent) {
memcg->swappiness = mem_cgroup_swappiness(parent);
@@ -5131,7 +5132,7 @@ static void mem_cgroup_css_reset(struct cgroup_subsys_state *css)
page_counter_set_max(&memcg->tcpmem, PAGE_COUNTER_MAX);
page_counter_set_min(&memcg->memory, 0);
page_counter_set_low(&memcg->memory, 0);
- memcg->high = PAGE_COUNTER_MAX;
+ WRITE_ONCE(memcg->high, PAGE_COUNTER_MAX);
memcg->soft_limit = PAGE_COUNTER_MAX;
memcg_wb_domain_size_changed(memcg);
}
@@ -5947,7 +5948,7 @@ static ssize_t memory_high_write(struct kernfs_open_file *of,
if (err)
return err;

- memcg->high = high;
+ WRITE_ONCE(memcg->high, high);

for (;;) {
unsigned long nr_pages = page_counter_read(&memcg->memory);
--
2.25.1
\
 
 \ /
  Last update: 2020-03-12 18:33    [W:0.060 / U:8.632 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site