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Wed, 12 Jan 2022 19:24:52 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 621AAAE04D; Wed, 12 Jan 2022 19:33:56 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 90FE3AE055; Wed, 12 Jan 2022 19:33:51 +0000 (GMT) Received: from hbathini-workstation.ibm.com.com (unknown [9.163.19.140]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 12 Jan 2022 19:33:51 +0000 (GMT) From: Hari Bathini To: akpm@linux-foundation.org, david@redhat.com, linux-mm@kvack.org, mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org Cc: osalvador@suse.de, mike.kravetz@oracle.com, mahesh@linux.ibm.com, sourabhjain@linux.ibm.com, Hari Bathini Subject: [PATCH v2 0/2] powerpc/fadump: handle CMA activation failure appropriately Date: Thu, 13 Jan 2022 01:03:38 +0530 Message-Id: <20220112193340.149020-1-hbathini@linux.ibm.com> X-Mailer: git-send-email 2.34.1 MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: aUbcMrs3jZINGIJonUwPz5PSXE-NameG X-Proofpoint-GUID: tfYbYqAmFZ1OXI6KsQ4wf0kDKKDiHvXS X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2022-01-12_05,2022-01-11_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 malwarescore=0 priorityscore=1501 bulkscore=0 adultscore=0 suspectscore=0 mlxscore=0 spamscore=0 mlxlogscore=999 impostorscore=0 clxscore=1015 phishscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2201120114 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: D1D5A18000E X-Stat-Signature: 1gk35ib1yx3mr1o6exnxegcsn5nnnnqn Authentication-Results: imf16.hostedemail.com; dkim=pass header.d=ibm.com header.s=pp1 header.b=FDVXwC9G; spf=pass (imf16.hostedemail.com: domain of hbathini@linux.ibm.com designates 148.163.158.5 as permitted sender) smtp.mailfrom=hbathini@linux.ibm.com; dmarc=pass (policy=none) header.from=ibm.com X-HE-Tag: 1642016047-43076 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: While commit a4e92ce8e4c8 ("powerpc/fadump: Reservationless firmware assisted dump"), introduced Linux kernel's Contiguous Memory Allocator (CMA) based reservation for fadump, it came with the assumption that the memory remains reserved even if CMA activation fails. It ensures no kernel pages reside in the reserved memory region, which can't be mapped into the /proc/vmcore. But commit 072355c1cf2d ("mm/cma: expose all pages to the buddy if activation of an area fails") started returning all pages to buddy allocator if CMA activation fails. This led to warning messages like below while running crash-utility on vmcore of a kernel having above two commits: crash: seek error: kernel virtual address: as reserved memory region ended up having kernel pages crash-utility was looking for. Fix this by introducing an option in CMA, to opt out from exposing pages to buddy allocator, on CMA activation failure. Changes in v2: * Replaced cma->free_pages_on_error with cma->reserve_pages_on_error & cma_dont_free_pages_on_error() with cma_reserve_pages_on_error() to avoid confusion and make the expectation on failure clearer. Hari Bathini (2): mm/cma: provide option to opt out from exposing pages on activation failure powerpc/fadump: opt out from freeing pages on cma activation failure arch/powerpc/kernel/fadump.c | 6 ++++++ include/linux/cma.h | 2 ++ mm/cma.c | 15 +++++++++++++-- mm/cma.h | 1 + 4 files changed, 22 insertions(+), 2 deletions(-) --=20 2.34.1