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Wed, 15 Apr 2026 04:41:06 +0000 (GMT) Message-ID: <94c902b07348fc8f406590c923387a532db4b7c6.camel@linux.ibm.com> Subject: Re: [PATCH v2] ppc/fadump: invoke kmsg_dump in fadump panic path From: Shirisha ganta To: Shivang Upadhyay , linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Cc: maddy@linux.ibm.com, mpe@ellerman.id.au, npiggin@gmail.com, chleroy@kernel.org, kees@kernel.org, tony.luck@intel.com, gpiccoli@igalia.com, ritesh.list@gmail.com, rppt@kernel.org, Hari Bathini , Mahesh Salgaonkar , Sourabh Jain Date: Wed, 15 Apr 2026 10:11:05 +0530 In-Reply-To: <20260412113057.46090-1-shivangu@linux.ibm.com> References: <20260412113057.46090-1-shivangu@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5 (3.28.5-26.el8_10) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-GUID: 68ROyXmkRqmFLvjzxpK4EqU-2elquNs3 X-Proofpoint-ORIG-GUID: _-vnYKujRhQ-vj7A0pf_FN45EzjgBhh7 X-Authority-Analysis: v=2.4 cv=WbE8rUhX c=1 sm=1 tr=0 ts=69df16eb cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=Y2IxJ9c9Rs8Kov3niI8_:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=pGLkceISAAAA:8 a=kTg7Ve40sHeub7HmClsA:9 a=QEXdDO2ut3YA:10 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDE1MDAzNyBTYWx0ZWRfX50sGbHGiW6Ua fHLTNb3kTBNQG3Pp+UM+YRTHILxgbpg1ps8hASaYGq2Ve2DAYK7LoZbqFJwW6pCkCrVhnyxeDcG G8TurZrUXz6C2/YSOF8Ab2Db9VEEjpZshvffi6SmDG+EF/cFygaZvw+FQUl9zIm+C2WW7bDSMSb 8ECxNbPRnqWKbWizZRDlmdGtagveIB4iN51WfMB98Pm1TKF4wIg0pt0CtdGK86M2H43TeFA/1co N17rcNCEpzNEC4G8kXDuAErXJfCcCdTt+Qtr5GpOI53qw2f4mt8yAQAy81goGw2czsoFAY5wSbq j1CtoZzX6Gsh90Wv4cmsiqDEGgNqQ4dPlxYINCacedSL8LnPc+WOg7TPpcnlsrSIHRE4E509/pt ZfqCPUWhq/hGyGzVXl41TeFP7PqDHCesIKiWxZ+n5jI9+2CLs9tpVOledQz69eaqA2rv05qBBia MXxfcC6J8uoauuXet3Q== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-14_04,2026-04-13_04,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 bulkscore=0 priorityscore=1501 spamscore=0 clxscore=1011 phishscore=0 impostorscore=0 adultscore=0 malwarescore=0 lowpriorityscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604070000 definitions=main-2604150037 On Sun, 2026-04-12 at 17:00 +0530, Shivang Upadhyay wrote: > fadump is registered in panic_notifier_list and gets triggered before > kmsg_dump_desc() in the panic path. As a result, kmsg_dumpers such as > pstore are not executed during fadump crashes. > > This is problematic because pstore provides a critical fallback > mechanism > for crash analysis. When fadump fails to successfully reboot the > system > or capture a dump, pstore logs may be the only available information > from > the crashed kernel. Without invoking kmsg_dump_desc() in the fadump > path, > we lose this valuable diagnostic data. > > Invoke kmsg_dump_desc() from the fadump panic handler, but only when > fadump is actually registered (checked via should_fadump_crash()). > This > ensures kmsg_dumpers are called without duplicating the call that > occurs > later in panic() when fadump is not active. > > The call is placed before crash_fadump() to ensure logs are captured > before the system attempts to trigger the firmware-assisted dump. > > Cc: Hari Bathini > Cc: Madhavan Srinivasan > Cc: Mahesh Salgaonkar > Cc: Michael Ellerman > Cc: Ritesh Harjani (IBM) > Reported-by: Shirisha G > Suggested-by: Sourabh Jain > Signed-off-by: Shivang Upadhyay > --- Hi, Tested this patch and dmesg-nvram file under /sys/fs/pstore is getting updated with this patch after triggering dump with fadump without this patch: # ls -ltrh total 0 -r--r--r--. 1 root root 6.5K Apr 2 06:22 dmesg-nvram-1 -r--r--r--. 1 root root 2.6K Apr 15 00:07 powerpc-common-nvram-6 -r--r--r--. 1 root root 2.1K Apr 15 00:07 rtas-nvram-1 -r--r--r--. 1 root root 688 Apr 15 00:07 powerpc-ofw-nvram-5 With this patch: # ls -ltrh total 0 -r--r--r--. 1 root root 6.4K Apr 15 00:36 dmesg-nvram-1 -r--r--r--. 1 root root 2.6K Apr 15 00:37 powerpc- common-nvram-6 -r--r--r--. 1 root root 2.1K Apr 15 00:37 rtas-nvram-1 -r- -r--r--. 1 root root 688 Apr 15 00:37 powerpc-ofw-nvram-5 Please add below tag Tested-by: Shirisha G > Changelog: > > v2: > address comments from Sourabh, and sashikio-ai > added should_fadump_crash() > > v1: > > https://lore.kernel.org/all/20260407054341.308710-1-shivangu@linux.ibm.com/ > --- > arch/powerpc/kernel/setup-common.c | 8 ++++++++ > 1 file changed, 8 insertions(+) > > diff --git a/arch/powerpc/kernel/setup-common.c > b/arch/powerpc/kernel/setup-common.c > index b1761909c23f..87afc8003a03 100644 > --- a/arch/powerpc/kernel/setup-common.c > +++ b/arch/powerpc/kernel/setup-common.c > @@ -68,6 +68,7 @@ > #include > #include > #include > +#include > > #include "setup.h" > > @@ -744,6 +745,13 @@ static int ppc_panic_fadump_handler(struct > notifier_block *this, > */ > hard_irq_disable(); > > + /* > + * Invoke kmsg_dump (e.g., pstore) before crash_fadump() as > fadump > + * runs before panic()'s kmsg_dump_desc() call. > + */ > + if (should_fadump_crash()) > + kmsg_dump_desc(KMSG_DUMP_PANIC, (char *)ptr); > + > /* > * If firmware-assisted dump has been registered then trigger > * its callback and let the firmware handles everything else.