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From: Dan Schatzberg <schatzberg.dan@gmail.com>
To: unlisted-recipients:; (no To-header on input)
Cc: Dan Schatzberg <schatzberg.dan@gmail.com>,
	Johannes Weiner <hannes@cmpxchg.org>, Tejun Heo <tj@kernel.org>,
	Chris Down <chris@chrisdown.name>,
	Shakeel Butt <shakeelb@google.com>, Jens Axboe <axboe@kernel.dk>,
	Alexander Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.cz>,
	Amir Goldstein <amir73il@gmail.com>,
	Li Zefan <lizefan@huawei.com>, Michal Hocko <mhocko@kernel.org>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Hugh Dickins <hughd@google.com>, Roman Gushchin <guro@fb.com>,
	Yang Shi <yang.shi@linux.alibaba.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>,
	"Peter Zijlstra (Intel)" <peterz@infradead.org>,
	Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	linux-block@vger.kernel.org (open list:BLOCK LAYER),
	linux-kernel@vger.kernel.org (open list),
	linux-fsdevel@vger.kernel.org (open list:FILESYSTEMS (VFS and
	infrastructure)),
	cgroups@vger.kernel.org (open list:CONTROL GROUP (CGROUP)),
	linux-mm@kvack.org (open list:CONTROL GROUP - MEMORY RESOURCE
	CONTROLLER (MEMCG))
Subject: [PATCH 3/4] mm: Charge active memcg when no mm is set
Date: Thu, 28 May 2020 09:54:38 -0400	[thread overview]
Message-ID: <20200528135444.11508-4-schatzberg.dan@gmail.com> (raw)
In-Reply-To: <20200528135444.11508-1-schatzberg.dan@gmail.com>

memalloc_use_memcg() worked for kernel allocations but was silently
ignored for user pages.

This patch establishes a precedence order for who gets charged:

1. If there is a memcg associated with the page already, that memcg is
   charged. This happens during swapin.

2. If an explicit mm is passed, mm->memcg is charged. This happens
   during page faults, which can be triggered in remote VMs (eg gup).

3. Otherwise consult the current process context. If it has configured
   a current->active_memcg, use that. Otherwise, current->mm->memcg.

Previously, if a NULL mm was passed to mem_cgroup_try_charge (case 3) it
would always charge the root cgroup. Now it looks up the current
active_memcg first (falling back to charging the root cgroup if not
set).

Signed-off-by: Dan Schatzberg <schatzberg.dan@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Chris Down <chris@chrisdown.name>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
---
 mm/memcontrol.c | 11 ++++++++---
 mm/shmem.c      |  4 ++--
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index a3b97f103966..383d88c1c105 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -6438,7 +6438,8 @@ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root,
  * @compound: charge the page as compound or small page
  *
  * Try to charge @page to the memcg that @mm belongs to, reclaiming
- * pages according to @gfp_mask if necessary.
+ * pages according to @gfp_mask if necessary. if @mm is NULL, try to
+ * charge to the active memcg.
  *
  * Returns 0 on success, with *@memcgp pointing to the charged memcg.
  * Otherwise, an error code is returned.
@@ -6482,8 +6483,12 @@ int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm,
 		}
 	}
 
-	if (!memcg)
-		memcg = get_mem_cgroup_from_mm(mm);
+	if (!memcg) {
+		if (!mm)
+			memcg = get_mem_cgroup_from_current();
+		else
+			memcg = get_mem_cgroup_from_mm(mm);
+	}
 
 	ret = try_charge(memcg, gfp_mask, nr_pages);
 
diff --git a/mm/shmem.c b/mm/shmem.c
index bd8840082c94..d2efa1a44311 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1618,7 +1618,7 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index,
 {
 	struct address_space *mapping = inode->i_mapping;
 	struct shmem_inode_info *info = SHMEM_I(inode);
-	struct mm_struct *charge_mm = vma ? vma->vm_mm : current->mm;
+	struct mm_struct *charge_mm = vma ? vma->vm_mm : NULL;
 	struct mem_cgroup *memcg;
 	struct page *page;
 	swp_entry_t swap;
@@ -1753,7 +1753,7 @@ static int shmem_getpage_gfp(struct inode *inode, pgoff_t index,
 	}
 
 	sbinfo = SHMEM_SB(inode->i_sb);
-	charge_mm = vma ? vma->vm_mm : current->mm;
+	charge_mm = vma ? vma->vm_mm : NULL;
 
 	page = find_lock_entry(mapping, index);
 	if (xa_is_value(page)) {
-- 
2.24.1


  parent reply	other threads:[~2020-05-28 13:55 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-28 13:54 [PATCH v6 0/4] Charge loop device i/o to issuing cgroup Dan Schatzberg
2020-05-28 13:54 ` [PATCH 1/4] loop: Use worker per cgroup instead of kworker Dan Schatzberg
2020-05-28 13:54 ` [PATCH 2/4] mm: support nesting memalloc_use_memcg() Dan Schatzberg
2020-05-28 13:54 ` Dan Schatzberg [this message]
2020-05-28 13:54 ` [PATCH 4/4] loop: Charge i/o to mem and blk cg Dan Schatzberg
2020-08-20 17:06 ` [PATCH v6 0/4] Charge loop device i/o to issuing cgroup Shakeel Butt
2020-08-21 15:04   ` Dan Schatzberg
2020-08-21 15:08     ` Jens Axboe
2020-08-21 16:01     ` Roman Gushchin
2020-08-21 16:27       ` Shakeel Butt
2020-08-21 20:05         ` Roman Gushchin
2020-08-21 20:23           ` Shakeel Butt
  -- strict thread matches above, loose matches on Subject: below --
2020-08-24 15:35 [PATCH v7 " Dan Schatzberg
2020-08-24 15:36 ` [PATCH 3/4] mm: Charge active memcg when no mm is set Dan Schatzberg
2020-04-20 22:39 [PATCH 0/4] Charge loop device i/o to issuing cgroup Dan Schatzberg
2020-04-20 22:39 ` [PATCH 3/4] mm: Charge active memcg when no mm is set Dan Schatzberg

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