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Tue, 20 Oct 2026 05:10:32 -0700 (PDT) Received: from pathway.suse.cz ([176.114.240.130]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48e1d823cfcsm5747053f8f.39.2026.10.20.05.10.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Oct 2026 05:10:32 -0700 (PDT) Date: Tue, 20 Oct 2026 14:10:29 +0200 From: Petr Mladek To: Zack Rusin Cc: Andrew Morton , Baoquan He , Mike Rapoport , Pasha Tatashin , Pratyush Yadav , Dave Young , Borislav Petkov , Ajay Kaher , Alexey Makhalov , x86@kernel.org, Joel Granados , Thomas Gleixner , Ingo Molnar , Dave Hansen , "H. Peter Anvin" , virtualization@lists.linux.dev, bcm-kernel-feedback-list@broadcom.com, linux-kernel@vger.kernel.org, John Ogness , Steven Rostedt , Sergey Senozhatsky , Kees Cook , Jonathan Corbet , Bo Gan , Brennan Lamoreaux , kexec@lists.infradead.org, linux-doc@vger.kernel.org, "Guilherme G. Piccoli" , Maaz Mombasawala , Shuah Khan , Randy Dunlap , Stephen Brennan , Michael Kelley , Ian Forbes Subject: Re: [PATCH v2 2/6] crash: Notify pre-kdump callbacks before switching kernels Message-ID: References: <9ef573cdbbf5e659eea16fa23afeaf2488049198.1790014793.git.zack.rusin@broadcom.com> X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9ef573cdbbf5e659eea16fa23afeaf2488049198.1790014793.git.zack.rusin@broadcom.com> On Mon 2026-09-28 13:55:36, Zack Rusin wrote: > Fatal x86 oopses can call crash_kexec() without reaching panic(). Run the > pre-kdump chain from __crash_kexec() as well, after finding a loaded image > under the kexec lock and capturing the original registers. > > This covers direct crash entry without moving all panic notifiers ahead > of kdump. A missing image or failed trylock leaves callbacks uncalled; > the shared guard skips callbacks already invoked by panic(). > > Link: https://lore.kernel.org/r/aquttpMVKX8e6zGB@pathway.suse.cz > Signed-off-by: Zack Rusin > --- > New in v2: cover direct crash-kexec entry in a separate core patch. > > kernel/crash_core.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/crash_core.c b/kernel/crash_core.c > index 2b36aa9fade0..5d9fe9e00f39 100644 > --- a/kernel/crash_core.c > +++ b/kernel/crash_core.c > @@ -23,6 +23,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -139,6 +140,7 @@ void __noclone __crash_kexec(struct pt_regs *regs) > struct pt_regs fixed_regs; > > crash_setup_regs(&fixed_regs, regs); > + panic_notify_pre_kdump(NULL); I understand why you did this. But it makes the code really hard to follow: + This code path will be called also by the 1st __crash_kexec() in vpanic() when "_crash_kexec_post_notifiers == false". It is the default. + The panic_notify_pre_kdump(buf) in vpanic(), added by 1st patch, is called when "_crash_kexec_post_notifiers == true" or when __crash_kexec() returns from some reason. None of this is obvious. I am going to think more about it. Best Regards, Petr > crash_save_vmcoreinfo(); > machine_crash_shutdown(&fixed_regs); > crash_cma_clear_pending_dma(); From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6E0E5606A31E for ; Tue, 20 Oct 2026 12:10:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=cGRU0Snr; dkim=fail reason="signature verification failed" (2048-bit key, unprotected) header.d=suse.com header.i=@suse.com header.a=rsa-sha256 header.s=google header.b=Tk5aRe9/ DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; 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Tue, 20 Oct 2026 05:10:32 -0700 (PDT) Received: from pathway.suse.cz ([176.114.240.130]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48e1d823cfcsm5747053f8f.39.2026.10.20.05.10.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 20 Oct 2026 05:10:32 -0700 (PDT) Date: Tue, 20 Oct 2026 14:10:29 +0200 From: Petr Mladek To: Zack Rusin Subject: Re: [PATCH v2 2/6] crash: Notify pre-kdump callbacks before switching kernels Message-ID: References: <9ef573cdbbf5e659eea16fa23afeaf2488049198.1790014793.git.zack.rusin@broadcom.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <9ef573cdbbf5e659eea16fa23afeaf2488049198.1790014793.git.zack.rusin@broadcom.com> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20261020_051034_682593_F6E31E7E X-CRM114-Status: GOOD ( 17.65 ) X-Spam-Score: -2.1 (--) X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-doc@vger.kernel.org, Kees Cook , Dave Hansen , Dave Young , Stephen Brennan , Bo Gan , "H. Peter Anvin" , Pasha Tatashin , Jonathan Corbet , Brennan Lamoreaux , x86@kernel.org, Joel Granados , Alexey Makhalov , Ingo Molnar , bcm-kernel-feedback-list@broadcom.com, Ajay Kaher , Baoquan He , John Ogness , virtualization@lists.linux.dev, Steven Rostedt , Maaz Mombasawala , Borislav Petkov , Shuah Khan , Michael Kelley , Pratyush Yadav , Randy Dunlap , kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Ian Forbes , Sergey Senozhatsky , Thomas Gleixner , Andrew Morton , Mike Rapoport Sender: "kexec" X-Spam-Status: No, score=-14.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_EF,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Mon 2026-09-28 13:55:36, Zack Rusin wrote: > Fatal x86 oopses can call crash_kexec() without reaching panic(). Run the > pre-kdump chain from __crash_kexec() as well, after finding a loaded image > under the kexec lock and capturing the original registers. > > This covers direct crash entry without moving all panic notifiers ahead > of kdump. A missing image or failed trylock leaves callbacks uncalled; > the shared guard skips callbacks already invoked by panic(). > > Link: https://lore.kernel.org/r/aquttpMVKX8e6zGB@pathway.suse.cz > Signed-off-by: Zack Rusin > --- > New in v2: cover direct crash-kexec entry in a separate core patch. > > kernel/crash_core.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/kernel/crash_core.c b/kernel/crash_core.c > index 2b36aa9fade0..5d9fe9e00f39 100644 > --- a/kernel/crash_core.c > +++ b/kernel/crash_core.c > @@ -23,6 +23,7 @@ > #include > #include > #include > +#include > > #include > #include > @@ -139,6 +140,7 @@ void __noclone __crash_kexec(struct pt_regs *regs) > struct pt_regs fixed_regs; > > crash_setup_regs(&fixed_regs, regs); > + panic_notify_pre_kdump(NULL); I understand why you did this. But it makes the code really hard to follow: + This code path will be called also by the 1st __crash_kexec() in vpanic() when "_crash_kexec_post_notifiers == false". It is the default. + The panic_notify_pre_kdump(buf) in vpanic(), added by 1st patch, is called when "_crash_kexec_post_notifiers == true" or when __crash_kexec() returns from some reason. None of this is obvious. I am going to think more about it. Best Regards, Petr > crash_save_vmcoreinfo(); > machine_crash_shutdown(&fixed_regs); > crash_cma_clear_pending_dma();