From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Schatzberg Subject: [PATCH 2/3] mm: Charge active memcg when no mm is set Date: Mon, 31 Aug 2020 11:36:59 -0400 Message-ID: <20200831153704.16848-3-schatzberg.dan@gmail.com> References: <20200831153704.16848-1-schatzberg.dan@gmail.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=hFNO1srh3AW4C+hy+7CfuD56Hs7de0B4v+mt5P6Q+8c=; b=SjePWpDm/dcOfaWyG090sIQ82qRogNC8U9o/SXOsilJibfKn37U7NrP6cYs9z13ajn 3ahnbXMI1dfgdzV1jsX4P8YPuyM1wY2QGXQiesxpHGGEg3Z23HYwzkk62guOns9HMJyO mv5bVZQTbHPtdEJ+eNlOenVGaVNmy48r50T0qx1KJrkByftLK+OzvzENGehdjQZ0EdVJ SbKPXAl9lN5Bz1sTMxYIYgFWi6dPAG2dwLhw1nXA9usckN3AXJXudsT9uUJdRuIs/Ntq 5nv1yGY0UIXNQDK7x6fl3OY/BjqkvDLJzoM8kbzBSnvSW8Q8tEl7Yp4cPcUq9xxnCReP 1UgQ== In-Reply-To: <20200831153704.16848-1-schatzberg.dan@gmail.com> Sender: linux-block-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Cc: Dan Schatzberg , Johannes Weiner , Tejun Heo , Chris Down , Shakeel Butt , Jens Axboe , Li Zefan , Michal Hocko , Vladimir Davydov , Andrew Morton , Hugh Dickins , Roman Gushchin , Yang Shi , Jakub Kicinski , "open list:BLOCK LAYER" , open list , "open list:CONTROL GROUP CGROUP" , "open list:CONTROL GROUP - MEMORY RESOURCE CONTROLLER MEMCG" 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 Acked-by: Johannes Weiner Acked-by: Tejun Heo Acked-by: Chris Down Reviewed-by: Shakeel Butt --- 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 e27ac6d79a32..877778b792da 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -6676,7 +6676,8 @@ void mem_cgroup_calculate_protection(struct mem_cgroup *root, * @gfp_mask: reclaim mode * * 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. Otherwise, an error code is returned. */ @@ -6712,8 +6713,12 @@ int mem_cgroup_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask) rcu_read_unlock(); } - 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); if (ret) diff --git a/mm/shmem.c b/mm/shmem.c index 271548ca20f3..1139f52ac4ee 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1695,7 +1695,7 @@ 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 page *page; swp_entry_t swap; int error; @@ -1809,7 +1809,7 @@ 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