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Fri, 16 Jul 2021 16:39:33 +0800 (CST) Received: from dggpeml500017.china.huawei.com (7.185.36.243) by dggemv703-chm.china.huawei.com (10.3.19.46) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Fri, 16 Jul 2021 16:45:13 +0800 Received: from huawei.com (10.175.103.91) by dggpeml500017.china.huawei.com (7.185.36.243) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2176.2; Fri, 16 Jul 2021 16:45:13 +0800 From: Yang Yingliang To: , , CC: , , , , Subject: [PATCH -next] memcg: fix sleep in invalid context in cgroup_rstat_flush() Date: Fri, 16 Jul 2021 16:48:05 +0800 Message-ID: <20210716084805.273744-1-yangyingliang@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Type: text/plain X-Originating-IP: [10.175.103.91] X-ClientProxiedBy: dggems701-chm.china.huawei.com (10.3.19.178) To dggpeml500017.china.huawei.com (7.185.36.243) X-CFilter-Loop: Reflected X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: F26B3F000396 X-Stat-Signature: 3jap619pst44mo9seayts8g9rb48oasw Authentication-Results: imf17.hostedemail.com; dkim=none; dmarc=pass (policy=none) header.from=huawei.com; spf=pass (imf17.hostedemail.com: domain of yangyingliang@huawei.com designates 45.249.212.255 as permitted sender) smtp.mailfrom=yangyingliang@huawei.com X-HE-Tag: 1626425117-939846 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: When start the kernel, I got this report: [ 13.787531][ T248] BUG: sleeping function called from invalid context= at kernel/cgroup/rstat.c:200 [ 13.788799][ T248] in_atomic(): 1, irqs_disabled(): 0, non_block: 0, = pid: 248, name: kworker/u8:3 [ 13.789971][ T248] 3 locks held by kworker/u8:3/248: [ 13.790638][ T248] #0: ffff888100100138 ((wq_completion)events_unbou= nd){+.+.}-{0:0}, at: process_one_work+0x942/0x17d0 [ 13.792170][ T248] #1: ffffc900018bfe00 (stats_flush_work){+.+.}-{0:= 0}, at: process_one_work+0x977/0x17d0 [ 13.793477][ T248] #2: ffffffff8baccf78 (stats_flush_lock){+.+.}-{2:= 2}, at: mem_cgroup_flush_stats+0xd/0x50 [ 13.794815][ T248] Preemption disabled at: [ 13.794821][ T248] [<0000000000000000>] 0x0 [ 13.795951][ T248] CPU: 2 PID: 248 Comm: kworker/u8:3 Tainted: G = W 5.14.0-rc1-next-20210716+ #342 [ 13.797287][ T248] Hardware name: QEMU Standard PC (i440FX + PIIX, 19= 96), BIOS 1.13.0-1ubuntu1.1 04/01/2014 [ 13.798564][ T248] Workqueue: events_unbound flush_memcg_stats_work [ 13.799400][ T248] Call Trace: [ 13.799817][ T248] dump_stack_lvl+0xcd/0x134 [ 13.800405][ T248] ___might_sleep.cold.155+0x1f2/0x238 [ 13.801107][ T248] cgroup_rstat_flush+0x1c/0x50 [ 13.801724][ T248] mem_cgroup_flush_stats+0x39/0x50 [ 13.802131][ T248] process_one_work+0xa6c/0x17d0 [ 13.802131][ T248] ? pwq_dec_nr_in_flight+0x360/0x360 [ 13.802131][ T248] ? do_raw_spin_lock+0x121/0x2d0 [ 13.802131][ T248] worker_thread+0x8c/0xda0 [ 13.802131][ T248] ? process_one_work+0x17d0/0x17d0 [ 13.802131][ T248] kthread+0x3d5/0x4c0 [ 13.802131][ T248] ? set_kthread_struct+0x130/0x130 [ 13.802131][ T248] ret_from_fork+0x1f/0x30 To fix this, move stats_flush_lock into cgroup_rstat_flush() after might_= sleep(), unlock stats_flush_lock before sleep in cgroup_rstat_flush_locked() and l= ock stats_flush_lock after wake up. Fixes: 42265e014ac7 ("memcg: infrastructure to flush memcg stats") Signed-off-by: Yang Yingliang --- kernel/cgroup/rstat.c | 7 +++++++ mm/memcontrol.c | 5 ----- 2 files changed, 7 insertions(+), 5 deletions(-) diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c index 7f0e58917432..d7ce96ba0105 100644 --- a/kernel/cgroup/rstat.c +++ b/kernel/cgroup/rstat.c @@ -5,6 +5,7 @@ =20 static DEFINE_SPINLOCK(cgroup_rstat_lock); static DEFINE_PER_CPU(raw_spinlock_t, cgroup_rstat_cpu_lock); +static DEFINE_SPINLOCK(stats_flush_lock); =20 static void cgroup_base_stat_flush(struct cgroup *cgrp, int cpu); =20 @@ -175,8 +176,10 @@ static void cgroup_rstat_flush_locked(struct cgroup = *cgrp, bool may_sleep) if (may_sleep && (need_resched() || spin_needbreak(&cgroup_rstat_lock))) { spin_unlock_irq(&cgroup_rstat_lock); + spin_unlock(&stats_flush_lock); if (!cond_resched()) cpu_relax(); + spin_lock(&stats_flush_lock); spin_lock_irq(&cgroup_rstat_lock); } } @@ -199,9 +202,13 @@ void cgroup_rstat_flush(struct cgroup *cgrp) { might_sleep(); =20 + if (!spin_trylock(&stats_flush_lock)) + return; + spin_lock_irq(&cgroup_rstat_lock); cgroup_rstat_flush_locked(cgrp, true); spin_unlock_irq(&cgroup_rstat_lock); + spin_unlock(&stats_flush_lock); } =20 /** diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 456f5310ea59..c6b0f5b41893 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -109,7 +109,6 @@ static DECLARE_DEFERRABLE_WORK(stats_flush_dwork, flu= sh_memcg_stats_dwork); static void flush_memcg_stats_work(struct work_struct *w); static DECLARE_WORK(stats_flush_work, flush_memcg_stats_work); static DEFINE_PER_CPU(unsigned int, stats_flush_threshold); -static DEFINE_SPINLOCK(stats_flush_lock); =20 #define THRESHOLDS_EVENTS_TARGET 128 #define SOFTLIMIT_EVENTS_TARGET 1024 @@ -5355,11 +5354,7 @@ static void mem_cgroup_css_reset(struct cgroup_sub= sys_state *css) =20 void mem_cgroup_flush_stats(void) { - if (!spin_trylock(&stats_flush_lock)) - return; - cgroup_rstat_flush(root_mem_cgroup->css.cgroup); - spin_unlock(&stats_flush_lock); } =20 static void flush_memcg_stats_dwork(struct work_struct *w) --=20 2.25.1