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Thu, 06 Apr 2023 19:58:37 -0400 X-MC-Unique: QClurESXN1SjjlcoxeaNlw-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 2A98785C069; Thu, 6 Apr 2023 23:58:36 +0000 (UTC) Received: from localhost (ovpn-12-86.pek2.redhat.com [10.72.12.86]) by smtp.corp.redhat.com (Postfix) with ESMTPS id CC8CD18EC6; Thu, 6 Apr 2023 23:58:34 +0000 (UTC) Date: Fri, 7 Apr 2023 07:58:31 +0800 From: Baoquan He To: Eric DeVolder Cc: linux-kernel@vger.kernel.org, x86@kernel.org, kexec@lists.infradead.org, ebiederm@xmission.com, dyoung@redhat.com, vgoyal@redhat.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, nramas@linux.microsoft.com, thomas.lendacky@amd.com, robh@kernel.org, efault@gmx.de, rppt@kernel.org, david@redhat.com, sourabhjain@linux.ibm.com, konrad.wilk@oracle.com, boris.ostrovsky@oracle.com Subject: Re: [PATCH v21 2/7] crash: add generic infrastructure for crash hotplug support Message-ID: References: <20230404180326.6890-1-eric.devolder@oracle.com> <20230404180326.6890-3-eric.devolder@oracle.com> <80767ccc-ffd4-9cb9-44e4-a8d4f0e13853@oracle.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <80767ccc-ffd4-9cb9-44e4-a8d4f0e13853@oracle.com> X-Scanned-By: MIMEDefang 3.1 on 10.11.54.5 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230406_165842_248780_94E75E12 X-CRM114-Status: GOOD ( 30.60 ) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+kexec=archiver.kernel.org@lists.infradead.org On 04/06/23 at 11:10am, Eric DeVolder wrote: > > > On 4/6/23 06:04, Baoquan He wrote: > > On 04/04/23 at 02:03pm, Eric DeVolder wrote: > > ...... > > > +static void crash_handle_hotplug_event(unsigned int hp_action, unsigned int cpu) > > > +{ > > > + struct kimage *image; > > > + > > > + /* Obtain lock while changing crash information */ > > > + if (!kexec_trylock()) { > > > + pr_info("kexec_trylock() failed, elfcorehdr may be inaccurate\n"); > > > + return; > > > + } > > > + > > > + /* Check kdump is not loaded */ > > > + if (!kexec_crash_image) > > > + goto out; > > > + > > > + image = kexec_crash_image; > > > + > > > + if (hp_action == KEXEC_CRASH_HP_ADD_CPU || > > > + hp_action == KEXEC_CRASH_HP_REMOVE_CPU) > > > + pr_debug("hp_action %u, cpu %u\n", hp_action, cpu); > > > + else > > > + pr_debug("hp_action %u\n", hp_action); > > > > Seems we passed in the cpu number just for printing here. Wondering why > > we don't print out hot added/removed memory ranges. Is the cpu number > > printing necessary? > > > Baoquan, > > Ah, actually until recently it was used to track the 'offlinecpu' in this > function, but tglx pointed out that was un-necessary. That resulted in > dropping the code in this function dealing with offlinecpu, leaving this as > its only use in this function. > > The printing of cpu number is not necessary, but helpful; I use it for debugging. OK, I see. I am not requesting memory range printing, just try to prove cpu number printing is not so justified. If it's helpful, I am OK with it. Let's see if other people have concern about this. > > The printing of memory range is also not necessary, but in order to do that, > should we choose to do so, requires passing in the memory range to this > function. This patch series did do this early on, and by v7 I dropped it at > your urging (https://lore.kernel.org/lkml/20220401183040.1624-1-eric.devolder@oracle.com/). > At the time, I provided it since I considered this generic infrastructure, > but I could not defend it since x86 didn't need it. However, PPC now needs > this, and is now carrying this as part of PPC support of CRASH_HOTPLUG (https://lore.kernel.org/linuxppc-dev/20230312181154.278900-6-sourabhjain@linux.ibm.com/T/#u). > > If you'd rather I pickup the memory range handling again, I can do that. I > think I'd likely change this function to be: > > void crash_handle_hotplug_event(unsigned int hp_action, unsigned int cpu, > struct memory_notify *mhp); > > where on a CPU op the 'cpu' parameter would be valid and 'mhp' NULL, and on a memory op, > the 'mhp' would be valid and 'cpu' parameter invalid(0). > > I'd likely then stuff these two parameters into struct kimage so that it can > be utilized by arch-specific handler, if needed. > > And of course, would print out the memory range for debug purposes. > > Let me know what you think. _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec