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d=linutronix.de; s=2020e; t=1664206125; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=9nbCVQlF5qlRYS1gBGpsvqLakPTcaKItqwHxbBmwhEU=; b=olKpBUea9DZ42RA47FqvYpgoEm5m73lP7JG6MFSQ5veDZbxevd8Nlr14YrjeQMjjL8v3DX ondOGzqBh1a9lyCw== From: Sebastian Andrzej Siewior To: Vlastimil Babka Cc: Uladzislau Rezki , Florian Westphal , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, netdev@vger.kernel.org, netfilter-devel@vger.kernel.org, Martin Zaharinov Subject: Re: [PATCH mm] mm: fix BUG with kvzalloc+GFP_ATOMIC Message-ID: References: <20220923103858.26729-1-fw@strlen.de> <20220923133512.GE22541@breakpoint.cc> <20220923145409.GF22541@breakpoint.cc> <76d0cb2b-a963-b867-4399-3e3c4828ecc4@suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <76d0cb2b-a963-b867-4399-3e3c4828ecc4@suse.cz> ARC-Seal: i=1; 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b=eMVJMhgSqDoYKnkvVIQQQ1FZn0GaT6K0O0CQg5dT2N+TUVpYE85TANsO18fJPqrB8lWJ8d uy6hbbSgnui6Tt0qtLiSZxGLGS7KwkHc/rEmTWv94bsUPXtlqztnC8LJkHFYAnkbJimHwf W1v/Diev0mu7FHCO6SMvuP/mDIGfU6U= X-Stat-Signature: zrif94t6ou93q669oqier73swhso85t8 X-Rspam-User: X-Rspamd-Server: rspam04 Authentication-Results: imf27.hostedemail.com; dkim=pass header.d=linutronix.de header.s=2020 header.b=l95NVTon; dkim=pass header.d=linutronix.de header.s=2020e header.b=olKpBUea; dmarc=pass (policy=none) header.from=linutronix.de; spf=pass (imf27.hostedemail.com: domain of bigeasy@linutronix.de designates 193.142.43.55 as permitted sender) smtp.mailfrom=bigeasy@linutronix.de X-Rspamd-Queue-Id: 0EB0540003 X-HE-Tag: 1664206126-601737 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: On 2022-09-26 17:03:48 [+0200], Vlastimil Babka wrote: > > Doing the "p = kmalloc(sizeof(*p), GFP_ATOMIC);" from an atomic context > > is also a problem nowadays. Such code should be fixed across the kernel > > because of PREEMPT_RT support. You should make sure that the context in question is atomic on PREEMPT_RT before fixing it. My guess here is that it is average the softirq (NAPI) callback which is fine. > But the "atomic context" here is different, no? Calling kmalloc() from IRQ > handlers AFAIK is ok as IRQ handlers are threaded on PREEMPT_RT. Calling it > inside an local_irq_disable() would be a problem on the other hand. But then > under e.g. spin_lock_irqsave() could be ok as those don't really disable > irqs on RT. correct. Sebastian