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t=1716898668; bh=thkilVwsc5+/E9dlNQwbhLVQMP7WluQzYZN1Agek5fQ=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=JxZlZLnQbVOpdyxPuOOShDwTA4njtQfdwSDyyflpNIedLQrbkISnZw+mGdd7xaLs2 MRkcRaBHEZ50sWtM4TDJJt97DCar+id3e2VZaCwDIQUcvJis0NnrQlPgJsLG0R7+ed Q1WE9NRXZK48cbv4giKbZZMnlREq2wuNwjt49QE1D7H0OZhX/4PPWkddxUkEmpgpc6 W8HsypC+AdPzAgnFk3Alwevyiadlfqsg/KHcX17V+dKZdJrours3NKSjybkFIs5uB1 Pot20RdxIv3++zqAyGGpcPqgl09Avvaz5Klij/GhBg+uNn8QVRnxFZFEFOMcFTd6ga BMyfUBrESx7Xw== Message-ID: <800ceb7a-7c48-442b-912c-d55c6a1aaacb@kernel.org> Date: Tue, 28 May 2024 14:17:44 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] memcg: simple cleanup of stats update functions 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: <20240420232505.2768428-1-shakeel.butt@linux.dev> <20240527152200.P1rU7FaG@linutronix.de> <86006806-4ffc-4330-ab4b-29215ab2c98c@kernel.org> <20240528075623.oFcU1JLj@linutronix.de> <69c0e008-ddde-4a38-b856-b765dc2b9745@kernel.org> <20240528101906.ts4NjHvU@linutronix.de> From: "Vlastimil Babka (SUSE)" In-Reply-To: <20240528101906.ts4NjHvU@linutronix.de> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: 97E3A1C001F X-Rspam-User: X-Rspamd-Server: rspam12 X-Stat-Signature: 3gp5584y31mrfjjhy96ydgy71yeowruq X-HE-Tag: 1716898669-521866 X-HE-Meta: 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 nVGzMzjj Pw2E4iQp5R4QGWC4onFUnSQNs6tGwm/OuhS7VTq5IsKAxIBGEclGR0+ty1exyOFeJHsLmz2QiLzbNUwJP1WxCMX6Z1KvCMk32U3HnKLcOfQLx0Exovbo43wNo2GTsGngdExRt1i5155+L89vkYpk7JEubdovS5sx3JKjMqRpc/Pgnls5l2ovO1HWMSdJtZUyPa2VnryPC02nNICMr/UTxyoKYnvPffoM6RmttuAWG8QRocI8= 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 12:19 PM, Sebastian Andrzej Siewior wrote: > On 2024-05-28 10:10:50 [+0200], Vlastimil Babka (SUSE) wrote: >> > I don't mind sending a patch. I'm just not sure if the lock is the right >> > thing to do. However it should ensure that interrupts are disabled on >> > !RT for the sake of the counter update (if observed in IRQ context). >> >> Looks like some places there use VM_WARN_ON_IRQS_ENABLED() that's turned off >> for PREEMPT_RT, so maybe that's what should replace the current >> lockdep_assert, perhaps together with >> lockdep_assert_held(this_cpu_ptr(&memcg_stock.stock_lock)); >> >> But also __mod_memcg_lruvec_state() already has that VM_WARN_ON. > > This "VM_WARN_ON_IRQS_ENABLED" is the initial assert for "interrupts > must be disabled while change the counter". > You want to replace it with lockdep? Part of its requirement was that it > yells with lockdep disabled. No I meant the other way around, that we'de use VM_WARN_ON_IRQS_ENABLED instead of the current lockdep_assert() that doesn't work on RT. > Currently I am leaning towards removing the > lockdep_assert_irqs_disabled() from __mod_objcg_mlstate(). Nothing but > the counter need it and they have their own check. So? Yeah that might be sufficient. > Sebastian