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Wed, 12 Jan 2022 19:34:53 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 52775AE053; Wed, 12 Jan 2022 19:34:53 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7FED2AE051; Wed, 12 Jan 2022 19:34:48 +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 19:34:48 +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 2/2] powerpc/fadump: opt out from freeing pages on cma activation failure Date: Thu, 13 Jan 2022 01:03:40 +0530 Message-Id: <20220112193340.149020-3-hbathini@linux.ibm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220112193340.149020-1-hbathini@linux.ibm.com> References: <20220112193340.149020-1-hbathini@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: dNCm72Urdu393CqVIGa1vFH9fM5rH5pe X-Proofpoint-ORIG-GUID: Lfzo64ukQWg5tbf7RGJpScNXAtNA_-lc 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 adultscore=0 impostorscore=0 malwarescore=0 mlxscore=0 lowpriorityscore=0 bulkscore=0 mlxlogscore=999 priorityscore=1501 clxscore=1015 spamscore=0 phishscore=0 suspectscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2201120114 X-Rspamd-Server: rspam04 X-Rspamd-Queue-Id: BFD51A000A X-Stat-Signature: d4kpoz3s7iwzdkoc54zuscb7nqu7g3cf Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=ibm.com header.s=pp1 header.b=lErzy3qW; spf=pass (imf15.hostedemail.com: domain of hbathini@linux.ibm.com designates 148.163.156.1 as permitted sender) smtp.mailfrom=hbathini@linux.ibm.com; dmarc=pass (policy=none) header.from=ibm.com X-HE-Tag: 1642016105-226109 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: With commit a4e92ce8e4c8 ("powerpc/fadump: Reservationless firmware assisted dump"), Linux kernel's Contiguous Memory Allocator (CMA) based reservation was introduced in fadump. That change was aimed at using CMA to let applications utilize the memory reserved for fadump while blocking it from being used for kernel pages. The assumption was, even if CMA activation fails for whatever reason, the memory still remains reserved to avoid it from being used for kernel pages. But commit 072355c1cf2d ("mm/cma: expose all pages to the buddy if activation of an area fails") breaks this assumption as it started exposing all pages to buddy allocator on CMA activation failure. It 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: To fix this problem, opt out from exposing pages to buddy allocator on CMA activation failure for fadump reserved memory. Signed-off-by: Hari Bathini --- arch/powerpc/kernel/fadump.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/powerpc/kernel/fadump.c b/arch/powerpc/kernel/fadump.c index b7ceb041743c..82058b52e34a 100644 --- a/arch/powerpc/kernel/fadump.c +++ b/arch/powerpc/kernel/fadump.c @@ -112,6 +112,12 @@ static int __init fadump_cma_init(void) return 1; } =20 + /* + * If CMA activation fails, keep the pages reserved, instead of + * exposing them to buddy allocator. Same as 'fadump=3Dnocma' case. + */ + cma_reserve_pages_on_error(fadump_cma); + /* * So we now have successfully initialized cma area for fadump. */ --=20 2.34.1