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[2003:cb:c704:3500:b8a3:191c:eae:cc05]) by smtp.gmail.com with ESMTPSA id u8-20020a5d4688000000b002c5544b3a69sm10081903wrq.89.2023.03.06.06.07.27 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 06 Mar 2023 06:07:27 -0800 (PST) Message-ID: <7161f75e-9f40-f881-84b8-1eaaec0b0e3f@redhat.com> Date: Mon, 6 Mar 2023 15:07:26 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.8.0 Subject: Re: [PATCH] powerpc/mm: fix mmap_lock bad unlock To: Laurent Dufour , linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org, Sachin Sant , Suren Baghdasaryan References: <20230306135520.4222-1-ldufour@linux.ibm.com> From: David Hildenbrand Organization: Red Hat In-Reply-To: <20230306135520.4222-1-ldufour@linux.ibm.com> X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Stat-Signature: rsh1zxe6ybpxof44wbmj3nd9jdt444dm X-Rspam-User: X-Rspamd-Queue-Id: 905E4100012 X-Rspamd-Server: rspam06 X-HE-Tag: 1678111651-920282 X-HE-Meta: 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 xJKnF938 FK6NZWLLEEJjvxRn+gNmzvv8x8HPyVRH4GobHQZrsQ0V+dM4yJZGymUjrH2/BS+ody9v+L6eQCM1o0qtdMOEJsj0sovHzzSvfmswXTjgeUkt6gNs/JLJ5n8qs5nxL5HduNUJsd1kJa4UHPdRm2TCnmj12gNdpYu8OhcaReAn9no6sUN7qz18ZWG10mqTtjsSDDW8GGg8PBlwOSwtYiBOat6WBBGcnCoH13VEtDlYymtDX2zrUvHuWAZ/Tq6GLYx6TBmuYS2idWcrxP6lB79bBqbMEBnpBVyKouL2cHeRVf/TeU8O06sXLQNrRBbprRx4DB8KiKj9yS1I18RxT3XfPG1Ebhc/DLuCsOopviHekmsitJyZmIZ3+G3Bi25zx8yzmzx4gE5wqBe22cjHjMYusWWBbqIg/A6lvpNAHaL6+yi8Ubr78C7x0AvhzXlMJV4rjn83SnzS97i0w7LQ= 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: 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. -- Thanks, David / dhildenb