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Fri, 06 Nov 2026 13:50:59 +0000 X-Mizu-Trace-ID: 821439f0cfeaeec5 X-Migadu-Flow: FLOW_OUT From: Usama Arif To: Mikhail Zaslonko Cc: Usama Arif , Andrew Morton , Baoquan He , Mike Rapoport , Pasha Tatashin , Pratyush Yadav , Dave Young , Jiri Bohac , David Hildenbrand , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , kexec@lists.infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] kdump: Give crashkernel CMA areas unique names Date: Fri, 6 Nov 2026 05:50:55 -0800 Message-ID: <20261106135056.790448-1-usama.arif@linux.dev> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261106104309.3669583-1-zaslonko@linux.ibm.com> References: X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: zj53fxj6iku4joppw7nzgefe7htkkygu X-Rspamd-Queue-Id: 5F3761C0004 X-Rspam-User: X-Rspamd-Server: rspam11 X-Spam-Status: No, score=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1793973061-696242 X-HE-Meta: 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 NoVVL8PZ E0lx7LgauxyzzqgJlxsGrLJxB1mJsT2hu7XV4VRTLv0RwVVwydIIVixtkf/pAP1/8jxtmSdAT19eyjGcCDJxHL/VoyuWZAOCoGVfCtW5cui5bhzpkri/tbjjJF0lN76qyeXCxg2kCPntFJgdBj3c37k6OUfCIKcBw7GKzS4ZC4mpzoipx5XBqrhfcH8fGahHk/lrx23c26rp/s+IFhIuPSkqflnG/bBcjT6B04UBtngMVhfibymSePiGprGBMpMaK+UdrcVRhc+W5/bIslrbPxpqlVw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Fri, 6 Nov 2026 11:43:09 +0100 Mikhail Zaslonko wrote: > reserve_crashkernel_cma() names every CMA area it reserves > "crashkernel". If the requested size can't be reserved in one piece, > it falls back to several smaller areas, all with the same name. > With CONFIG_CMA_SYSFS, cma_sysfs_init() then fails to create the second > directory: > > sysfs: cannot create duplicate filename '/kernel/mm/cma/crashkernel' > > and the error path removes the sysfs entries of all CMA areas. > > With CONFIG_CMA_DEBUGFS, debugfs refuses the duplicate directories as > well: > > debugfs: 'crashkernel' already exists in 'cma' > > so only the first area shows up in debugfs. > > Keep the name of the first area and add the index to the others: > crashkernel, crashkernel1, crashkernel2, ... > > Fixes: ab475510e042 ("kdump: implement reserve_crashkernel_cma") > Signed-off-by: Mikhail Zaslonko > --- > Found while adding crashkernel CMA support for s390. > > kernel/crash_reserve.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) Thanks for the fix and pointing me to it in [1]! Acked-by: Usama Arif [1] https://lore.kernel.org/all/20261106104309.3669583-1-zaslonko@linux.ibm.com/ > > diff --git a/kernel/crash_reserve.c b/kernel/crash_reserve.c > index eee37a11380c..e58318b1e092 100644 > --- a/kernel/crash_reserve.c > +++ b/kernel/crash_reserve.c > @@ -483,10 +483,16 @@ void __init reserve_crashkernel_cma(unsigned long long cma_size) > while (cma_size > reserved_size && > crashk_cma_cnt < CRASHKERNEL_CMA_RANGES_MAX) { > > + char name[CMA_MAX_NAME]; > struct cma *res; > > + /* CMA area names show up in sysfs and debugfs, keep them unique */ > + if (crashk_cma_cnt) > + snprintf(name, sizeof(name), "crashkernel%d", crashk_cma_cnt); > + else > + strscpy(name, "crashkernel"); > if (cma_declare_contiguous(0, request_size, 0, 0, 0, false, > - "crashkernel", &res)) { > + name, &res)) { > /* reservation failed, try half-sized blocks */ > if (request_size <= PAGE_SIZE) > break; > > base-commit: f66469d9905b39d2c260a15d7d6db450f4db67c1 > -- > 2.55.0 > >