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Content-Language: en-US To: Sebastian Andrzej Siewior Cc: Shakeel Butt , Andrew Morton , Johannes Weiner , Michal Hocko , Roman Gushchin , Muchun Song , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Thomas Gleixner References: <20240528121928.i-Gu7Jvg@linutronix.de> <09e085bb-f09e-4901-a2dd-a0b789bb8a4d@kernel.org> <20240528134027.OxDASsS3@linutronix.de> <20240528141341.rz_rytN_@linutronix.de> From: "Vlastimil Babka (SUSE)" In-Reply-To: <20240528141341.rz_rytN_@linutronix.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 8C7EF160003 X-Stat-Signature: medyucwwgtf5z5r1akkghtfd51nubhi7 X-Rspam-User: X-Rspamd-Server: rspam04 X-HE-Tag: 1716905959-936826 X-HE-Meta: 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 5K79jmZ2 ncTJbrsGIbdh1mrUAIWWSiWqDU7OIc/4sNq07VK2vjmT7pN44hNVFrKPdt4zCV1GXXLHqss/wC6s0SJ6kiC/jFjNbw12jHVjmIlvbY+Lpngbcr6OIegsI6nTkzqPoa2eQg2vTxGVuWVkCLiNjzhOiJHLqQkIZppawc4xPzx58UOv6xccEMUs3vyXxbWQjF/UTua/b8t3Wnkb6F/jlnhwL3dVzn73lnrIsi2llWphld8GzTU/fbnTHCTZgoP3BYPfj+DU9UBpSnEQrelId+uu2jjpQMNdkgQAZC/PSD0KYGfaE6/CjFpoiNDfOE2CKNMsGYh8QsZLoPnsq5fc= 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: List-Subscribe: List-Unsubscribe: On 5/28/24 4:13 PM, Sebastian Andrzej Siewior wrote: > The assert was introduced in the commit cited below as an insurance that > the semantic is the same after the local_irq_save() has been removed and > the function has been made static. > > The original requirement to disable interrupt was due the modification > of per-CPU counters which require interrupts to be disabled because the > counter update operation is not atomic and some of the counters are > updated from interrupt context. > > All callers of __mod_objcg_mlstate() acquire a lock > (memcg_stock.stock_lock) which disables interrupts on !PREEMPT_RT and > the lockdep assert is satisfied. On PREEMPT_RT the interrupts are not > disabled and the assert triggers. > > The safety of the counter update is already ensured by > VM_WARN_ON_IRQS_ENABLED() which is part of __mod_memcg_lruvec_state() and > does not require yet another check. > > Remove the lockdep assert from __mod_objcg_mlstate(). > > Fixes: 91882c1617c15 ("memcg: simple cleanup of stats update functions") > Link: https://lore.kernel.org/r/20240528121928.i-Gu7Jvg@linutronix.de > Signed-off-by: Sebastian Andrzej Siewior Acked-by: Vlastimil Babka mm-hotfixes as it's a rc1 regression > --- > On 2024-05-28 15:44:51 [+0200], Vlastimil Babka (SUSE) wrote: >> I think just s/memcg_stats_lock()/__mod_memcg_lruvec_state()/ in your >> phrasing, since we are removing the lockdep assert from path that calls >> __mod_memcg_lruvec_state() and not memcg_stats_lock()? >> Or am I missing something? > > Yeah, makes sense. > > mm/memcontrol.c | 2 -- > 1 file changed, 2 deletions(-) > > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -3147,8 +3147,6 @@ static inline void __mod_objcg_mlstate(s > struct mem_cgroup *memcg; > struct lruvec *lruvec; > > - lockdep_assert_irqs_disabled(); > - > rcu_read_lock(); > memcg = obj_cgroup_memcg(objcg); > lruvec = mem_cgroup_lruvec(memcg, pgdat);