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Mon, 13 Apr 2026 10:11:03 +0000 (GMT) Date: Mon, 13 Apr 2026 15:41:01 +0530 From: Mahesh J Salgaonkar To: Shivang Upadhyay Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, 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 , Shirisha G , Sourabh Jain Subject: Re: [PATCH v2] ppc/fadump: invoke kmsg_dump in fadump panic path Message-ID: Reply-To: mahesh@linux.ibm.com References: <20260412113057.46090-1-shivangu@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260412113057.46090-1-shivangu@linux.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-Reinject: loops=2 maxloops=12 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDEzMDA5NiBTYWx0ZWRfX4vAbFqFtr/TX gk3cBypSkJIvCUd6LxpxK/JrZYi7eIwgk3ujaunEs9Lm/3ODuIdr7CanqGneSGsDULJFwkoUYYI WDagmIJOa1KAnFHQ6E6uQZZesC41UaEfTRp7gm6eJX4yRO43bt/TgHrk/MauV8mqxO0QnSrQtao 71rzOWKOC5ubcEgoeWqN96H+fsrox4vV7CqBfay3juhlQuIuXQbFt4jfACyyKQbMgcxr80w95rz Z2uUbaYqnoaBRGKHhPyjc/MzCy9ETJGX5+inEYW+ub2G4NkxgATaqpmySz0M6Cf9c6WOdJoQdCK T8303Yp0j1eyHReBVhXV/+UGUuLSkaSSFBZF5onHWjJPSJX6F5b6/nRjCfq0V09RxgWf9PqYEkO EePYEXps6UialenVDh0bZvScFuvVb2O6IkugIQq6NLuYFb0ae4R2TImG7GzWPSnHLqD+oP37ffb OwUVNpvDPO15p7IpJ4Q== X-Proofpoint-GUID: B60NViVCc_7uerikIIw-TolAXwccSV9d X-Proofpoint-ORIG-GUID: 7ar2RWTPLcEOZG4C2B4Gt9QJGO15uhhi X-Authority-Analysis: v=2.4 cv=YemNIQRf c=1 sm=1 tr=0 ts=69dcc13e cx=c_pps a=3Bg1Hr4SwmMryq2xdFQyZA==:117 a=3Bg1Hr4SwmMryq2xdFQyZA==:17 a=kj9zAlcOel0A:10 a=A5OVakUREuEA:10 a=VkNPw1HP01LnGYTKEx00:22 a=RnoormkPH1_aCDwRdu11:22 a=V8glGbnc2Ofi9Qvn3v5h:22 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=pGLkceISAAAA:8 a=WMeMqPS48f8hHYZQQtcA:9 a=CjuIK1q_8ugA:10 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=2026-04-13_02,2026-04-13_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 adultscore=0 priorityscore=1501 lowpriorityscore=0 clxscore=1011 impostorscore=0 bulkscore=0 malwarescore=0 suspectscore=0 phishscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2604010000 definitions=main-2604130096 On 2026-04-12 17:00:57 Sun, 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 > --- > 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); > + Looks good to me. Reviewed-by: Mahesh Salgaonkar Thanks, -Mahesh. > /* > * If firmware-assisted dump has been registered then trigger > * its callback and let the firmware handles everything else. > -- > 2.53.0 > > -- Mahesh J Salgaonkar