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d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=BoEr7WGwjUHLgvmjABjLm7MYZbCdiBk18X5QycU0/Ew=; b=pWiYdsjJF5iTjWrKmjrlqwuhqOsz3O01QUOaVMRRMW7HGKom6wKK0MYk9eux29K4k3 hILZv7CC2S1rgv0mdELnzvdE08gFtvh/Eesbz+kLXAQCVHc7EhWksaqCVC+Gj5JFKD45 ACLB6wMzXfabQ/5LwG5+dvNmB8HqMs7juVPVdL8Ekpn/JM1Ncmax6jdnGaoMmoe1jGc6 IL3Xlu6wfMRjoiq3DPYG+likXIcrUdDGxH8oiYEK2B95H3raa8OF58eZbNLt5lPSLGoD o/fnv6laW5CH5lGdpya15+6sojWvPFUwgTqfDtDcLETuAtVq1M9I6ZY2utZKQEjxMxgh 5UNA== X-Gm-Message-State: AOAM531oHpnGbO7alvsOEa7pBXOznoacNYwfZNb/Yq2C3tBDFYfD7cC2 Lh3oGd6E1bKmDs9mmGtkMUU= X-Google-Smtp-Source: ABdhPJzSxRMbHr3768Ryko5wzIqRvsiHRmA9C0S8rOoKZePdY55COev8ggirAorBv7qmRa+qVwvqBg== X-Received: by 2002:ad4:50d0:: with SMTP id e16mr26048338qvq.37.1617029346580; Mon, 29 Mar 2021 07:49:06 -0700 (PDT) From: Dan Schatzberg Cc: Jens Axboe , Tejun Heo , Zefan Li , Johannes Weiner , Andrew Morton , Michal Hocko , Vladimir Davydov , Hugh Dickins , Shakeel Butt , Roman Gushchin , Yang Shi , Muchun Song , Alex Shi , Alexander Duyck , Yafang Shao , Wei Yang , linux-block@vger.kernel.org (open list:BLOCK LAYER), linux-kernel@vger.kernel.org (open list), cgroups@vger.kernel.org (open list:CONTROL GROUP (CGROUP)), linux-mm@kvack.org (open list:MEMORY MANAGEMENT), Chris Down Subject: [PATCH 1/3] loop: Use worker per cgroup instead of kworker Date: Mon, 29 Mar 2021 07:48:23 -0700 Message-Id: <20210329144829.1834347-2-schatzberg.dan@gmail.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210329144829.1834347-1-schatzberg.dan@gmail.com> References: <20210329144829.1834347-1-schatzberg.dan@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" Existing uses of loop device may have multiple cgroups reading/writing to the same device. Simply charging resources for I/O to the backing file could result in priority inversion where one cgroup gets synchronously blocked, holding up all other I/O to the loop device. In order to avoid this priority inversion, we use a single workqueue where each work item is a "struct loop_worker" which contains a queue of struct loop_cmds to issue. The loop device maintains a tree mapping blk css_id -> loop_worker. This allows each cgroup to independently make forward progress issuing I/O to the backing file. There is also a single queue for I/O associated with the rootcg which can be used in cases of extreme memory shortage where we cannot allocate a loop_worker. The locking for the tree and queues is fairly heavy handed - we acquire a per-loop-device spinlock any time either is accessed. The existing implementation serializes all I/O through a single thread anyways, so I don't believe this is any worse. Fixes-from: Colin Ian King Signed-off-by: Dan Schatzberg --- drivers/block/loop.c | 207 ++++++++++++++++++++++++++++++++++++------- drivers/block/loop.h | 12 ++- 2 files changed, 182 insertions(+), 37 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index d58d68f3c7cd..5c18e6b856c2 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -71,7 +71,6 @@ #include #include #include -#include #include #include #include @@ -84,6 +83,8 @@ =20 #include =20 +#define LOOP_IDLE_WORKER_TIMEOUT (60 * HZ) + static DEFINE_IDR(loop_index_idr); static DEFINE_MUTEX(loop_ctl_mutex); =20 @@ -921,27 +922,83 @@ static void loop_config_discard(struct loop_device *l= o) q->limits.discard_alignment =3D 0; } =20 -static void loop_unprepare_queue(struct loop_device *lo) -{ - kthread_flush_worker(&lo->worker); - kthread_stop(lo->worker_task); -} +struct loop_worker { + struct rb_node rb_node; + struct work_struct work; + struct list_head cmd_list; + struct list_head idle_list; + struct loop_device *lo; + struct cgroup_subsys_state *css; + unsigned long last_ran_at; +}; =20 -static int loop_kthread_worker_fn(void *worker_ptr) -{ - current->flags |=3D PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO; - return kthread_worker_fn(worker_ptr); -} +static void loop_workfn(struct work_struct *work); +static void loop_rootcg_workfn(struct work_struct *work); +static void loop_free_idle_workers(struct timer_list *timer); =20 -static int loop_prepare_queue(struct loop_device *lo) +static void loop_queue_work(struct loop_device *lo, struct loop_cmd *cmd) { - kthread_init_worker(&lo->worker); - lo->worker_task =3D kthread_run(loop_kthread_worker_fn, - &lo->worker, "loop%d", lo->lo_number); - if (IS_ERR(lo->worker_task)) - return -ENOMEM; - set_user_nice(lo->worker_task, MIN_NICE); - return 0; + struct rb_node **node =3D &(lo->worker_tree.rb_node), *parent =3D NULL; + struct loop_worker *cur_worker, *worker =3D NULL; + struct work_struct *work; + struct list_head *cmd_list; + + spin_lock_irq(&lo->lo_work_lock); + + if (!cmd->css) + goto queue_work; + + node =3D &lo->worker_tree.rb_node; + + while (*node) { + parent =3D *node; + cur_worker =3D container_of(*node, struct loop_worker, rb_node); + if (cur_worker->css =3D=3D cmd->css) { + worker =3D cur_worker; + break; + } else if ((long)cur_worker->css < (long)cmd->css) { + node =3D &(*node)->rb_left; + } else { + node =3D &(*node)->rb_right; + } + } + if (worker) + goto queue_work; + + worker =3D kzalloc(sizeof(struct loop_worker), GFP_NOWAIT | __GFP_NOWARN); + /* + * In the event we cannot allocate a worker, just queue on the + * rootcg worker + */ + if (!worker) + goto queue_work; + + worker->css =3D cmd->css; + css_get(worker->css); + INIT_WORK(&worker->work, loop_workfn); + INIT_LIST_HEAD(&worker->cmd_list); + INIT_LIST_HEAD(&worker->idle_list); + worker->lo =3D lo; + rb_link_node(&worker->rb_node, parent, node); + rb_insert_color(&worker->rb_node, &lo->worker_tree); +queue_work: + if (worker) { + /* + * We need to remove from the idle list here while + * holding the lock so that the idle timer doesn't + * free the worker + */ + if (!list_empty(&worker->idle_list)) + list_del_init(&worker->idle_list); + work =3D &worker->work; + cmd_list =3D &worker->cmd_list; + } else { + work =3D &lo->rootcg_work; + cmd_list =3D &lo->rootcg_cmd_list; + } + list_add_tail(&cmd->list_entry, cmd_list); + queue_work(lo->workqueue, work); + spin_unlock_irq(&lo->lo_work_lock); } =20 static void loop_update_rotational(struct loop_device *lo) @@ -1127,12 +1184,27 @@ static int loop_configure(struct loop_device *lo, f= mode_t mode, !file->f_op->write_iter) lo->lo_flags |=3D LO_FLAGS_READ_ONLY; =20 - error =3D loop_prepare_queue(lo); - if (error) + error =3D -EFBIG; + size =3D get_loop_size(lo, file); + if ((loff_t)(sector_t)size !=3D size) goto out_unlock; + lo->workqueue =3D alloc_workqueue("loop%d", + WQ_UNBOUND | WQ_FREEZABLE, + 0, + lo->lo_number); + if (!lo->workqueue) { + error =3D -ENOMEM; + goto out_unlock; + } =20 set_disk_ro(lo->lo_disk, (lo->lo_flags & LO_FLAGS_READ_ONLY) !=3D 0); =20 + INIT_WORK(&lo->rootcg_work, loop_rootcg_workfn); + INIT_LIST_HEAD(&lo->rootcg_cmd_list); + INIT_LIST_HEAD(&lo->idle_worker_list); + lo->worker_tree =3D RB_ROOT; + timer_setup(&lo->timer, loop_free_idle_workers, + TIMER_DEFERRABLE); lo->use_dio =3D lo->lo_flags & LO_FLAGS_DIRECT_IO; lo->lo_device =3D bdev; lo->lo_backing_file =3D file; @@ -1200,6 +1272,7 @@ static int __loop_clr_fd(struct loop_device *lo, bool= release) int err =3D 0; bool partscan =3D false; int lo_number; + struct loop_worker *pos, *worker; =20 mutex_lock(&lo->lo_mutex); if (WARN_ON_ONCE(lo->lo_state !=3D Lo_rundown)) { @@ -1219,6 +1292,18 @@ static int __loop_clr_fd(struct loop_device *lo, boo= l release) /* freeze request queue during the transition */ blk_mq_freeze_queue(lo->lo_queue); =20 + destroy_workqueue(lo->workqueue); + spin_lock_irq(&lo->lo_work_lock); + list_for_each_entry_safe(worker, pos, &lo->idle_worker_list, + idle_list) { + list_del(&worker->idle_list); + rb_erase(&worker->rb_node, &lo->worker_tree); + css_put(worker->css); + kfree(worker); + } + spin_unlock_irq(&lo->lo_work_lock); + del_timer_sync(&lo->timer); + spin_lock_irq(&lo->lo_lock); lo->lo_backing_file =3D NULL; spin_unlock_irq(&lo->lo_lock); @@ -1255,7 +1340,6 @@ static int __loop_clr_fd(struct loop_device *lo, bool= release) =20 partscan =3D lo->lo_flags & LO_FLAGS_PARTSCAN && bdev; lo_number =3D lo->lo_number; - loop_unprepare_queue(lo); out_unlock: mutex_unlock(&lo->lo_mutex); if (partscan) { @@ -2026,7 +2110,7 @@ static blk_status_t loop_queue_rq(struct blk_mq_hw_ct= x *hctx, } else #endif cmd->css =3D NULL; - kthread_queue_work(&lo->worker, &cmd->work); + loop_queue_work(lo, cmd); =20 return BLK_STS_OK; } @@ -2056,26 +2140,82 @@ static void loop_handle_cmd(struct loop_cmd *cmd) } } =20 -static void loop_queue_work(struct kthread_work *work) +static void loop_set_timer(struct loop_device *lo) +{ + timer_reduce(&lo->timer, jiffies + LOOP_IDLE_WORKER_TIMEOUT); +} + +static void loop_process_work(struct loop_worker *worker, + struct list_head *cmd_list, struct loop_device *lo) { - struct loop_cmd *cmd =3D - container_of(work, struct loop_cmd, work); + int orig_flags =3D current->flags; + struct loop_cmd *cmd; =20 - loop_handle_cmd(cmd); + current->flags |=3D PF_LOCAL_THROTTLE | PF_MEMALLOC_NOIO; + spin_lock_irq(&lo->lo_work_lock); + while (!list_empty(cmd_list)) { + cmd =3D container_of( + cmd_list->next, struct loop_cmd, list_entry); + list_del(cmd_list->next); + spin_unlock_irq(&lo->lo_work_lock); + + loop_handle_cmd(cmd); + cond_resched(); + + spin_lock_irq(&lo->lo_work_lock); + } + + /* + * We only add to the idle list if there are no pending cmds + * *and* the worker will not run again which ensures that it + * is safe to free any worker on the idle list + */ + if (worker && !work_pending(&worker->work)) { + worker->last_ran_at =3D jiffies; + list_add_tail(&worker->idle_list, &lo->idle_worker_list); + loop_set_timer(lo); + } + spin_unlock_irq(&lo->lo_work_lock); + current->flags =3D orig_flags; } =20 -static int loop_init_request(struct blk_mq_tag_set *set, struct request *r= q, - unsigned int hctx_idx, unsigned int numa_node) +static void loop_workfn(struct work_struct *work) { - struct loop_cmd *cmd =3D blk_mq_rq_to_pdu(rq); + struct loop_worker *worker =3D + container_of(work, struct loop_worker, work); + loop_process_work(worker, &worker->cmd_list, worker->lo); +} =20 - kthread_init_work(&cmd->work, loop_queue_work); - return 0; +static void loop_rootcg_workfn(struct work_struct *work) +{ + struct loop_device *lo =3D + container_of(work, struct loop_device, rootcg_work); + loop_process_work(NULL, &lo->rootcg_cmd_list, lo); +} + +static void loop_free_idle_workers(struct timer_list *timer) +{ + struct loop_device *lo =3D container_of(timer, struct loop_device, timer); + struct loop_worker *pos, *worker; + + spin_lock_irq(&lo->lo_work_lock); + list_for_each_entry_safe(worker, pos, &lo->idle_worker_list, + idle_list) { + if (time_is_after_jiffies(worker->last_ran_at + + LOOP_IDLE_WORKER_TIMEOUT)) + break; + list_del(&worker->idle_list); + rb_erase(&worker->rb_node, &lo->worker_tree); + css_put(worker->css); + kfree(worker); + } + if (!list_empty(&lo->idle_worker_list)) + loop_set_timer(lo); + spin_unlock_irq(&lo->lo_work_lock); } =20 static const struct blk_mq_ops loop_mq_ops =3D { .queue_rq =3D loop_queue_rq, - .init_request =3D loop_init_request, .complete =3D lo_complete_rq, }; =20 @@ -2164,6 +2304,7 @@ static int loop_add(struct loop_device **l, int i) mutex_init(&lo->lo_mutex); lo->lo_number =3D i; spin_lock_init(&lo->lo_lock); + spin_lock_init(&lo->lo_work_lock); disk->major =3D LOOP_MAJOR; disk->first_minor =3D i << part_shift; disk->fops =3D &lo_fops; diff --git a/drivers/block/loop.h b/drivers/block/loop.h index a3c04f310672..9289c1cd6374 100644 --- a/drivers/block/loop.h +++ b/drivers/block/loop.h @@ -14,7 +14,6 @@ #include #include #include -#include #include =20 /* Possible states of device */ @@ -54,8 +53,13 @@ struct loop_device { =20 spinlock_t lo_lock; int lo_state; - struct kthread_worker worker; - struct task_struct *worker_task; + spinlock_t lo_work_lock; + struct workqueue_struct *workqueue; + struct work_struct rootcg_work; + struct list_head rootcg_cmd_list; + struct list_head idle_worker_list; + struct rb_root worker_tree; + struct timer_list timer; bool use_dio; bool sysfs_inited; =20 @@ -66,7 +70,7 @@ struct loop_device { }; =20 struct loop_cmd { - struct kthread_work work; + struct list_head list_entry; bool use_aio; /* use AIO interface to handle I/O */ atomic_t ref; /* only for aio */ long ret; --=20 2.30.2 From nobody Sun May 5 17:32:49 2024 Delivered-To: importer2@patchew.org Received-SPF: pass (zohomail.com: domain of vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; envelope-from=linux-kernel-owner@vger.kernel.org; helo=vger.kernel.org; Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail(p=none dis=none) header.from=gmail.com ARC-Seal: i=1; a=rsa-sha256; t=1617029423; cv=none; d=zohomail.com; s=zohoarc; b=ng5mt5EFgwNlNwXDW0NbTFZWYiazj824ud3L/sgCR7Yw2ONJZvBbbsXgKukzN1nVl1D9sgeA2h1ikyjOhg+Ls7XW5g8Krd+5LCrARAW8Oycd7nh+HRImJzkgTej82p9CFyhnGezHZg+4Aq7rW75hU/cl1Oh7uibkLvyXujwFe4o= ARC-Message-Signature: i=1; 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(no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" set_active_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 there is an active_memcg, use that. Otherwise, current->mm->memcg. Previously, if a NULL mm was passed to mem_cgroup_charge (case 3) it would always charge the root cgroup. Now it looks up the 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/filemap.c | 2 +- mm/memcontrol.c | 72 ++++++++++++++++++++++++++++--------------------- mm/shmem.c | 4 +-- 3 files changed, 44 insertions(+), 34 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index eeeb8e2cc36a..63fd980e863a 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -872,7 +872,7 @@ noinline int __add_to_page_cache_locked(struct page *pa= ge, page->index =3D offset; =20 if (!huge) { - error =3D mem_cgroup_charge(page, current->mm, gfp); + error =3D mem_cgroup_charge(page, NULL, gfp); if (error) goto error; charged =3D true; diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 668d1d7c2645..adc618814fd2 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -884,13 +884,38 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_s= truct *p) } EXPORT_SYMBOL(mem_cgroup_from_task); =20 +static __always_inline struct mem_cgroup *active_memcg(void) +{ + if (in_interrupt()) + return this_cpu_read(int_active_memcg); + else + return current->active_memcg; +} + +static __always_inline struct mem_cgroup *get_active_memcg(void) +{ + struct mem_cgroup *memcg; + + rcu_read_lock(); + memcg =3D active_memcg(); + /* remote memcg must hold a ref. */ + if (memcg && WARN_ON_ONCE(!css_tryget(&memcg->css))) + memcg =3D root_mem_cgroup; + rcu_read_unlock(); + + return memcg; +} + /** * get_mem_cgroup_from_mm: Obtain a reference on given mm_struct's memcg. * @mm: mm from which memcg should be extracted. It can be NULL. * - * Obtain a reference on mm->memcg and returns it if successful. Otherwise - * root_mem_cgroup is returned. However if mem_cgroup is disabled, NULL is - * returned. + * Obtain a reference on mm->memcg and returns it if successful. If mm + * is NULL, then the memcg is chosen as follows: + * 1) The active memcg, if set. + * 2) current->mm->memcg, if available + * 3) root memcg + * If mem_cgroup is disabled, NULL is returned. */ struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_struct *mm) { @@ -899,13 +924,19 @@ struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_s= truct *mm) if (mem_cgroup_disabled()) return NULL; =20 + /* + * Page cache insertions can happen without an + * actual mm context, e.g. during disk probing + * on boot, loopback IO, acct() writes etc. + */ + if (unlikely(!mm)) { + if (unlikely(active_memcg())) + return get_active_memcg(); + mm =3D current->mm; + } + rcu_read_lock(); do { - /* - * Page cache insertions can happen withou an - * actual mm context, e.g. during disk probing - * on boot, loopback IO, acct() writes etc. - */ if (unlikely(!mm)) memcg =3D root_mem_cgroup; else { @@ -919,28 +950,6 @@ struct mem_cgroup *get_mem_cgroup_from_mm(struct mm_st= ruct *mm) } EXPORT_SYMBOL(get_mem_cgroup_from_mm); =20 -static __always_inline struct mem_cgroup *active_memcg(void) -{ - if (in_interrupt()) - return this_cpu_read(int_active_memcg); - else - return current->active_memcg; -} - -static __always_inline struct mem_cgroup *get_active_memcg(void) -{ - struct mem_cgroup *memcg; - - rcu_read_lock(); - memcg =3D active_memcg(); - /* remote memcg must hold a ref. */ - if (memcg && WARN_ON_ONCE(!css_tryget(&memcg->css))) - memcg =3D root_mem_cgroup; - rcu_read_unlock(); - - return memcg; -} - static __always_inline bool memcg_kmem_bypass(void) { /* Allow remote memcg charging from any context. */ @@ -6549,7 +6558,8 @@ static int __mem_cgroup_charge(struct page *page, str= uct mem_cgroup *memcg, * @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. * * Do not use this for pages allocated for swapin. * diff --git a/mm/shmem.c b/mm/shmem.c index 78ab81a62b29..7c09276125d5 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1694,7 +1694,7 @@ static int shmem_swapin_page(struct inode *inode, pgo= ff_t index, { struct address_space *mapping =3D inode->i_mapping; struct shmem_inode_info *info =3D SHMEM_I(inode); - struct mm_struct *charge_mm =3D vma ? vma->vm_mm : current->mm; + struct mm_struct *charge_mm =3D vma ? vma->vm_mm : NULL; struct page *page; swp_entry_t swap; int error; @@ -1815,7 +1815,7 @@ static int shmem_getpage_gfp(struct inode *inode, pgo= ff_t index, } =20 sbinfo =3D SHMEM_SB(inode->i_sb); - charge_mm =3D vma ? vma->vm_mm : current->mm; + charge_mm =3D vma ? vma->vm_mm : NULL; =20 page =3D pagecache_get_page(mapping, index, FGP_ENTRY | FGP_HEAD | FGP_LOCK, 0); --=20 2.30.2 From nobody Sun May 5 17:32:49 2024 Delivered-To: importer2@patchew.org Received-SPF: pass (zohomail.com: domain of vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; envelope-from=linux-kernel-owner@vger.kernel.org; helo=vger.kernel.org; Authentication-Results: mx.zohomail.com; dkim=fail; spf=pass (zohomail.com: domain of vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; 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Mon, 29 Mar 2021 07:49:17 -0700 (PDT) From: Dan Schatzberg Cc: Jens Axboe , Tejun Heo , Zefan Li , Johannes Weiner , Andrew Morton , Michal Hocko , Vladimir Davydov , Hugh Dickins , Shakeel Butt , Roman Gushchin , Yang Shi , Muchun Song , Alex Shi , Alexander Duyck , Yafang Shao , Wei Yang , linux-block@vger.kernel.org (open list:BLOCK LAYER), linux-kernel@vger.kernel.org (open list), cgroups@vger.kernel.org (open list:CONTROL GROUP (CGROUP)), linux-mm@kvack.org (open list:MEMORY MANAGEMENT), Chris Down Subject: [PATCH 3/3] loop: Charge i/o to mem and blk cg Date: Mon, 29 Mar 2021 07:48:25 -0700 Message-Id: <20210329144829.1834347-4-schatzberg.dan@gmail.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210329144829.1834347-1-schatzberg.dan@gmail.com> References: <20210329144829.1834347-1-schatzberg.dan@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable To: unlisted-recipients:; (no To-header on input) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-ZohoMail-DKIM: fail (Header signature does not verify) Content-Type: text/plain; charset="utf-8" The current code only associates with the existing blkcg when aio is used to access the backing file. This patch covers all types of i/o to the backing file and also associates the memcg so if the backing file is on tmpfs, memory is charged appropriately. This patch also exports cgroup_get_e_css and int_active_memcg so it can be used by the loop module. Signed-off-by: Dan Schatzberg Acked-by: Johannes Weiner --- drivers/block/loop.c | 61 +++++++++++++++++++++++++------------- drivers/block/loop.h | 3 +- include/linux/memcontrol.h | 6 ++++ kernel/cgroup/cgroup.c | 1 + mm/memcontrol.c | 1 + 5 files changed, 51 insertions(+), 21 deletions(-) diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 5c18e6b856c2..96ade57c9f7c 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -78,6 +78,7 @@ #include #include #include +#include =20 #include "loop.h" =20 @@ -516,8 +517,6 @@ static void lo_rw_aio_complete(struct kiocb *iocb, long= ret, long ret2) { struct loop_cmd *cmd =3D container_of(iocb, struct loop_cmd, iocb); =20 - if (cmd->css) - css_put(cmd->css); cmd->ret =3D ret; lo_rw_aio_do_completion(cmd); } @@ -578,8 +577,6 @@ static int lo_rw_aio(struct loop_device *lo, struct loo= p_cmd *cmd, cmd->iocb.ki_complete =3D lo_rw_aio_complete; cmd->iocb.ki_flags =3D IOCB_DIRECT; cmd->iocb.ki_ioprio =3D IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0); - if (cmd->css) - kthread_associate_blkcg(cmd->css); =20 if (rw =3D=3D WRITE) ret =3D call_write_iter(file, &cmd->iocb, &iter); @@ -587,7 +584,6 @@ static int lo_rw_aio(struct loop_device *lo, struct loo= p_cmd *cmd, ret =3D call_read_iter(file, &cmd->iocb, &iter); =20 lo_rw_aio_do_completion(cmd); - kthread_associate_blkcg(NULL); =20 if (ret !=3D -EIOCBQUEUED) cmd->iocb.ki_complete(&cmd->iocb, ret, 0); @@ -928,7 +924,7 @@ struct loop_worker { struct list_head cmd_list; struct list_head idle_list; struct loop_device *lo; - struct cgroup_subsys_state *css; + struct cgroup_subsys_state *blkcg_css; unsigned long last_ran_at; }; =20 @@ -945,7 +941,7 @@ static void loop_queue_work(struct loop_device *lo, str= uct loop_cmd *cmd) =20 spin_lock_irq(&lo->lo_work_lock); =20 - if (!cmd->css) + if (!cmd->blkcg_css) goto queue_work; =20 node =3D &lo->worker_tree.rb_node; @@ -953,10 +949,10 @@ static void loop_queue_work(struct loop_device *lo, s= truct loop_cmd *cmd) while (*node) { parent =3D *node; cur_worker =3D container_of(*node, struct loop_worker, rb_node); - if (cur_worker->css =3D=3D cmd->css) { + if (cur_worker->blkcg_css =3D=3D cmd->blkcg_css) { worker =3D cur_worker; break; - } else if ((long)cur_worker->css < (long)cmd->css) { + } else if ((long)cur_worker->blkcg_css < (long)cmd->blkcg_css) { node =3D &(*node)->rb_left; } else { node =3D &(*node)->rb_right; @@ -968,13 +964,18 @@ static void loop_queue_work(struct loop_device *lo, s= truct loop_cmd *cmd) worker =3D kzalloc(sizeof(struct loop_worker), GFP_NOWAIT | __GFP_NOWARN); /* * In the event we cannot allocate a worker, just queue on the - * rootcg worker + * rootcg worker and issue the I/O as the rootcg */ - if (!worker) + if (!worker) { + cmd->blkcg_css =3D NULL; + if (cmd->memcg_css) + css_put(cmd->memcg_css); + cmd->memcg_css =3D NULL; goto queue_work; + } =20 - worker->css =3D cmd->css; - css_get(worker->css); + worker->blkcg_css =3D cmd->blkcg_css; + css_get(worker->blkcg_css); INIT_WORK(&worker->work, loop_workfn); INIT_LIST_HEAD(&worker->cmd_list); INIT_LIST_HEAD(&worker->idle_list); @@ -1298,7 +1299,7 @@ static int __loop_clr_fd(struct loop_device *lo, bool= release) idle_list) { list_del(&worker->idle_list); rb_erase(&worker->rb_node, &lo->worker_tree); - css_put(worker->css); + css_put(worker->blkcg_css); kfree(worker); } spin_unlock_irq(&lo->lo_work_lock); @@ -2103,13 +2104,18 @@ static blk_status_t loop_queue_rq(struct blk_mq_hw_= ctx *hctx, } =20 /* always use the first bio's css */ + cmd->blkcg_css =3D NULL; + cmd->memcg_css =3D NULL; #ifdef CONFIG_BLK_CGROUP - if (cmd->use_aio && rq->bio && rq->bio->bi_blkg) { - cmd->css =3D &bio_blkcg(rq->bio)->css; - css_get(cmd->css); - } else + if (rq->bio && rq->bio->bi_blkg) { + cmd->blkcg_css =3D &bio_blkcg(rq->bio)->css; +#ifdef CONFIG_MEMCG + cmd->memcg_css =3D + cgroup_get_e_css(cmd->blkcg_css->cgroup, + &memory_cgrp_subsys); +#endif + } #endif - cmd->css =3D NULL; loop_queue_work(lo, cmd); =20 return BLK_STS_OK; @@ -2121,13 +2127,28 @@ static void loop_handle_cmd(struct loop_cmd *cmd) const bool write =3D op_is_write(req_op(rq)); struct loop_device *lo =3D rq->q->queuedata; int ret =3D 0; + struct mem_cgroup *old_memcg =3D NULL; =20 if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY)) { ret =3D -EIO; goto failed; } =20 + if (cmd->blkcg_css) + kthread_associate_blkcg(cmd->blkcg_css); + if (cmd->memcg_css) + old_memcg =3D set_active_memcg( + mem_cgroup_from_css(cmd->memcg_css)); + ret =3D do_req_filebacked(lo, rq); + + if (cmd->blkcg_css) + kthread_associate_blkcg(NULL); + + if (cmd->memcg_css) { + set_active_memcg(old_memcg); + css_put(cmd->memcg_css); + } failed: /* complete non-aio request */ if (!cmd->use_aio || ret) { @@ -2206,7 +2227,7 @@ static void loop_free_idle_workers(struct timer_list = *timer) break; list_del(&worker->idle_list); rb_erase(&worker->rb_node, &lo->worker_tree); - css_put(worker->css); + css_put(worker->blkcg_css); kfree(worker); } if (!list_empty(&lo->idle_worker_list)) diff --git a/drivers/block/loop.h b/drivers/block/loop.h index 9289c1cd6374..cd24a81e00e6 100644 --- a/drivers/block/loop.h +++ b/drivers/block/loop.h @@ -76,7 +76,8 @@ struct loop_cmd { long ret; struct kiocb iocb; struct bio_vec *bvec; - struct cgroup_subsys_state *css; + struct cgroup_subsys_state *blkcg_css; + struct cgroup_subsys_state *memcg_css; }; =20 /* Support for loadable transfer modules */ diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index 4064c9dda534..df42be35b5fb 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -1178,6 +1178,12 @@ static inline struct mem_cgroup *get_mem_cgroup_from= _mm(struct mm_struct *mm) return NULL; } =20 +static inline +struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *css) +{ + return NULL; +} + static inline void mem_cgroup_put(struct mem_cgroup *memcg) { } diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index e049edd66776..8c84a5374238 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -577,6 +577,7 @@ struct cgroup_subsys_state *cgroup_get_e_css(struct cgr= oup *cgrp, rcu_read_unlock(); return css; } +EXPORT_SYMBOL_GPL(cgroup_get_e_css); =20 static void cgroup_get_live(struct cgroup *cgrp) { diff --git a/mm/memcontrol.c b/mm/memcontrol.c index adc618814fd2..4aacdf06c6c8 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -78,6 +78,7 @@ struct mem_cgroup *root_mem_cgroup __read_mostly; =20 /* Active memory cgroup to use from an interrupt context */ DEFINE_PER_CPU(struct mem_cgroup *, int_active_memcg); +EXPORT_PER_CPU_SYMBOL_GPL(int_active_memcg); =20 /* Socket memory accounting disabled? */ static bool cgroup_memory_nosocket; --=20 2.30.2