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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> From: "Vlastimil Babka (SUSE)" In-Reply-To: <20240528121928.i-Gu7Jvg@linutronix.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: sek9tiyyg7chckbax9ke8mkio1u1bt6h X-Rspamd-Queue-Id: A94D0180009 X-Rspam-User: X-Rspamd-Server: rspam01 X-HE-Tag: 1716899703-671407 X-HE-Meta: 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 VVRYvCdg lWnRaROcnza5E8S1c9fbzkhoXGGMALyqtrePPWBNsMkjMWWpWcD5sih8cy6R2KOU1Ypk02jHHJkb0IhteRI9n7VnyCu+107PFB8oW/JUF0wzLf4dHYpmBn0cC4u++hVjM3FypvcZ22jzoiW7/oyBmD4L2rK9IdvE/LKdJUs0eWYsm7fN5CeRwMyB9TxtLtJFlsXxdREQ6/vbvOAFs0keRFMIihVeRWFHYNv/cyhL03/t1uSZ63rtwnD4mMqklu8Pd07WT2VFQ6J6xlTRiEA1CXXBvQw== 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 2:19 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 memcg_stats_lock() and does > not require yet another check. I think here it's __mod_memcg_lruvec_state() doing the VM_WARN_ON_ as we don't go through memcg_stats_lock()? > Remove the lockdep assert from __mod_objcg_mlstate(). > > Fixes: 91882c1617c15 ("memcg: simple cleanup of stats update functions") > Signed-off-by: Sebastian Andrzej Siewior Acked-by: Vlastimil Babka mm-hotfixes as it's a rc1 regression > --- > 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);