From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qt1-f198.google.com (mail-qt1-f198.google.com [209.85.160.198]) by kanga.kvack.org (Postfix) with ESMTP id C9A1D8E0001 for ; Mon, 21 Jan 2019 17:02:37 -0500 (EST) Received: by mail-qt1-f198.google.com with SMTP id b16so21929768qtc.22 for ; Mon, 21 Jan 2019 14:02:37 -0800 (PST) Received: from a9-34.smtp-out.amazonses.com (a9-34.smtp-out.amazonses.com. [54.240.9.34]) by mx.google.com with ESMTPS id b6si2305201qtq.62.2019.01.21.14.02.37 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 21 Jan 2019 14:02:37 -0800 (PST) Date: Mon, 21 Jan 2019 22:02:36 +0000 From: Christopher Lameter Subject: Re: [PATCH] mm/slub: use WARN_ON() for some slab errors In-Reply-To: <1548063490-545-1-git-send-email-miles.chen@mediatek.com> Message-ID: <01000168726fcf15-81d8feb3-26f0-44d6-bbd8-62aa149118b5-000000@email.amazonses.com> References: <1548063490-545-1-git-send-email-miles.chen@mediatek.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Miles Chen Cc: Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org On Mon, 21 Jan 2019, miles.chen@mediatek.com wrote: > From: Miles Chen > > When debugging with slub.c, sometimes we have to trigger a panic in > order to get the coredump file. To do that, we have to modify slub.c and > rebuild kernel. To make debugging easier, use WARN_ON() for these slab > errors so we can dump stack trace by default or set panic_on_warn to > trigger a panic. These locations really should dump stack and not terminate. There is subsequent processing that should be done. Slub terminates by default. The messages you are modifying are only enabled if the user specified that special debugging should be one (typically via a kernel parameter slub_debug). It does not make sense to terminate the process here. 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[54.240.9.34]) by mx.google.com with ESMTPS id b6si2305201qtq.62.2019.01.21.14.02.37 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 21 Jan 2019 14:02:37 -0800 (PST) Received-SPF: pass (google.com: domain of 01000168726fcf15-81d8feb3-26f0-44d6-bbd8-62aa149118b5-000000@amazonses.com designates 54.240.9.34 as permitted sender) client-ip=54.240.9.34; Authentication-Results: mx.google.com; dkim=pass header.i=@amazonses.com header.s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug header.b=GuRKALKV; spf=pass (google.com: domain of 01000168726fcf15-81d8feb3-26f0-44d6-bbd8-62aa149118b5-000000@amazonses.com designates 54.240.9.34 as permitted sender) smtp.mailfrom=01000168726fcf15-81d8feb3-26f0-44d6-bbd8-62aa149118b5-000000@amazonses.com DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/simple; s=ug7nbtf4gccmlpwj322ax3p6ow6yfsug; d=amazonses.com; t=1548108156; h=Date:From:To:cc:Subject:In-Reply-To:Message-ID:References:MIME-Version:Content-Type:Feedback-ID; bh=OJCgqsaZ+wmR6x0X309IC98tvTtpLA7MmmS/XOpDQfc=; b=GuRKALKV2VCcr4jAbByx0u0oiNeiB4CSPat1WTFMtNriM8UmrZ/OntXWBFDYRvMe elpi405dUNq+OuDa8zhLri7SlJ3XFdTVKrMt1Z8CWIRgEu8L6W2+Q8ypTqiG8N7yfcN EESFVbiUwIJPQprgTCvW5t0Ar0FRiBrf/RmXa1ik= Date: Mon, 21 Jan 2019 22:02:36 +0000 From: Christopher Lameter X-X-Sender: cl@nuc-kabylake To: Miles Chen cc: Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-mediatek@lists.infradead.org Subject: Re: [PATCH] mm/slub: use WARN_ON() for some slab errors In-Reply-To: <1548063490-545-1-git-send-email-miles.chen@mediatek.com> Message-ID: <01000168726fcf15-81d8feb3-26f0-44d6-bbd8-62aa149118b5-000000@email.amazonses.com> References: <1548063490-545-1-git-send-email-miles.chen@mediatek.com> User-Agent: Alpine 2.21 (DEB 202 2017-01-01) MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" X-SES-Outgoing: 2019.01.21-54.240.9.34 Feedback-ID: 1.us-east-1.fQZZZ0Xtj2+TD7V5apTT/NrT6QKuPgzCT/IC7XYgDKI=:AmazonSES 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: Message-ID: <20190121220236.uvdpuKrvMiOuzaq1uS4jte1kkGM7RN5o0eoPh0wX2gA@z> On Mon, 21 Jan 2019, miles.chen@mediatek.com wrote: > From: Miles Chen > > When debugging with slub.c, sometimes we have to trigger a panic in > order to get the coredump file. To do that, we have to modify slub.c and > rebuild kernel. To make debugging easier, use WARN_ON() for these slab > errors so we can dump stack trace by default or set panic_on_warn to > trigger a panic. These locations really should dump stack and not terminate. There is subsequent processing that should be done. Slub terminates by default. The messages you are modifying are only enabled if the user specified that special debugging should be one (typically via a kernel parameter slub_debug). It does not make sense to terminate the process here.