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Tue, 24 Sep 2024 14:45:05 -0400 X-MC-Unique: SpljQlxaOWOK3fVkVgEt3w-1 Received: from mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (unknown [10.30.177.15]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 22B831936CD1; Tue, 24 Sep 2024 18:45:03 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.226.71]) by mx-prod-int-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with SMTP id 011881955D7A; Tue, 24 Sep 2024 18:36:48 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Tue, 24 Sep 2024 20:36:40 +0200 (CEST) Date: Tue, 24 Sep 2024 20:36:35 +0200 From: Oleg Nesterov To: "qiwu.chen" Cc: corbet@lwn.net, catalin.marinas@arm.com, will@kernel.org, paulmck@kernel.org, akpm@linux-foundation.org, linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org, "qiwu.chen" Subject: Re: [PATCH v4 2/2] arm64: show signal info for global init Message-ID: <20240924183634.GB17395@redhat.com> References: <20240924074341.37272-1-qiwu.chen@transsion.com> <20240924074341.37272-2-qiwu.chen@transsion.com> MIME-Version: 1.0 In-Reply-To: <20240924074341.37272-2-qiwu.chen@transsion.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20240924_114510_068231_AE634A70 X-CRM114-Status: GOOD ( 18.76 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Well, can't comment, I leave this to the arch/arm64/ maintainers. but let me add a bit of spam just for the record, On 09/24, qiwu.chen wrote: > > --- a/arch/arm64/kernel/traps.c > +++ b/arch/arm64/kernel/traps.c > @@ -247,12 +247,20 @@ static void arm64_show_signal(int signo, const char *str) > unsigned long esr = tsk->thread.fault_code; > struct pt_regs *regs = task_pt_regs(tsk); > > + /* > + * The signal sent to the global init needs to be shown, > + * which is useful for debugging kill init issue. > + */ > + if (unlikely(is_global_init(tsk))) > + goto dump; > + > /* Leave if the signal won't be shown */ > if (!show_unhandled_signals || > !unhandled_signal(tsk, signo) || > !__ratelimit(&rs)) > return; > > +dump: So what does this patch try to do? Note that unhandled_signal(tsk) returns true if is_global_init(tsk). So it seems that this patch just tries to bypass the show_unhandled_signals and __ratelimit() checks? Or what? OTOH. The is_global_init() check in unhandled_signal() (which predates the git history) doesn't look right to me. If init has a handler for, say, SIGSEGV, why should the kernel complain? I need to recheck this logic... Oleg.