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Mon, 6 Mar 2023 14:09:05 GMT Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2B3C92004F; Mon, 6 Mar 2023 14:09:05 +0000 (GMT) Received: from smtpav05.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id DDCDC2004D; Mon, 6 Mar 2023 14:09:04 +0000 (GMT) Received: from [9.101.4.33] (unknown [9.101.4.33]) by smtpav05.fra02v.mail.ibm.com (Postfix) with ESMTP; Mon, 6 Mar 2023 14:09:04 +0000 (GMT) Message-ID: Date: Mon, 6 Mar 2023 15:09:04 +0100 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:102.0) Gecko/20100101 Thunderbird/102.7.2 Subject: Re: [PATCH] powerpc/mm: fix mmap_lock bad unlock Content-Language: en-US To: David Hildenbrand , linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org References: <20230306135520.4222-1-ldufour@linux.ibm.com> <7161f75e-9f40-f881-84b8-1eaaec0b0e3f@redhat.com> From: Laurent Dufour In-Reply-To: <7161f75e-9f40-f881-84b8-1eaaec0b0e3f@redhat.com> Content-Type: text/plain; charset=UTF-8 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: ZCAAo8REJb2cV2Ico_GTnCpjlwwTWbBY X-Proofpoint-GUID: OQ96FBNbuO1igKID2f6Mnsb6fP9PMYyn Content-Transfer-Encoding: 8bit X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.942,Hydra:6.0.573,FMLib:17.11.170.22 definitions=2023-03-06_07,2023-03-06_01,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 clxscore=1015 malwarescore=0 adultscore=0 spamscore=0 impostorscore=0 lowpriorityscore=0 mlxlogscore=999 suspectscore=0 bulkscore=0 priorityscore=1501 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2212070000 definitions=main-2303060120 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Suren Baghdasaryan , linux-kernel@vger.kernel.org, Sachin Sant Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 06/03/2023 15:07:26, David Hildenbrand wrote: > On 06.03.23 14:55, Laurent Dufour wrote: >> When page fault is tried holding the per VMA lock, bad_access_pkey() and >> bad_access() should not be called because it is assuming the mmap_lock is >> held. >> In the case a bad access is detected, fall back to the default path, >> grabbing the mmap_lock to handle the fault and report the error. >> >> Fixes: 169db3bb4609 ("powerc/mm: try VMA lock-based page fault handling >> first") >> Reported-by: Sachin Sant >> Link: >> https://lore.kernel.org/linux-mm/842502FB-F99C-417C-9648-A37D0ECDC9CE@linux.ibm.com >> Cc: Suren Baghdasaryan >> Signed-off-by: Laurent Dufour >> --- >>   arch/powerpc/mm/fault.c | 8 ++------ >>   1 file changed, 2 insertions(+), 6 deletions(-) >> >> diff --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c >> index c7ae86b04b8a..e191b3ebd8d6 100644 >> --- a/arch/powerpc/mm/fault.c >> +++ b/arch/powerpc/mm/fault.c >> @@ -479,17 +479,13 @@ static int ___do_page_fault(struct pt_regs *regs, >> unsigned long address, >>         if (unlikely(access_pkey_error(is_write, is_exec, >>                          (error_code & DSISR_KEYFAULT), vma))) { >> -        int rc = bad_access_pkey(regs, address, vma); >> - >>           vma_end_read(vma); >> -        return rc; >> +        goto lock_mmap; >>       } >>         if (unlikely(access_error(is_write, is_exec, vma))) { >> -        int rc = bad_access(regs, address); >> - >>           vma_end_read(vma); >> -        return rc; >> +        goto lock_mmap; >>       } >>         fault = handle_mm_fault(vma, address, flags | >> FAULT_FLAG_VMA_LOCK, regs); > > IIUC, that commit is neither upstream not in mm-stable -- it's unstable. > Maybe raise that as a review comment in reply to the original patch, so we > can easily connect the dots and squash it into the original, problematic > patch that is still under review. > Oh yes, I missed that. I'll reply to the Suren's thread. Thanks, Laurent.