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Thu, 16 Mar 2023 10:57:01 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id HrZ2E/31EmTPcgAAMHmgww (envelope-from ); Thu, 16 Mar 2023 10:57:01 +0000 Message-ID: <74f2ea6c-f1a9-6dd7-260c-25e660f42379@suse.cz> Date: Thu, 16 Mar 2023 11:57:01 +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 09/10] mm/mmap: start distinguishing if vma can be removed in mergeability test Content-Language: en-US To: Lorenzo Stoakes , Andrew Morton Cc: "Liam R. Howlett" , Matthew Wilcox , linux-mm@kvack.org, linux-kernel@vger.kernel.org, patches@lists.linux.dev, maple-tree@lists.infradead.org References: <20230309111258.24079-1-vbabka@suse.cz> <20230309111258.24079-10-vbabka@suse.cz> <7e0e33a7-4e9b-4714-8d4b-9487c8d1f799@lucifer.local> From: Vlastimil Babka In-Reply-To: <7e0e33a7-4e9b-4714-8d4b-9487c8d1f799@lucifer.local> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: tywthmw8fypf89cqggd4h3oouoi3guqa X-Rspam-User: X-Rspamd-Queue-Id: F39F680011 X-Rspamd-Server: rspam06 X-HE-Tag: 1678964222-982149 X-HE-Meta: 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 WBgHANYu lxtiG9DWrr6bV1PewsdUDS4jWvRXU4/w/mtSAZ7sbHS2qAb+bRCr/Fr2I4A9Aq8+tuc0PnZ1aQSBVe0eplehe6bgfjHx6F7uQUsqUGLqJqi5UeCmPpkPWP92+ByiJ10ie3aWlGJs6+xarPR9Zm+5IRdj1mD5+OSx+FHDE0iVnpZVz/IPJNofXkLa+dPqVf3PClEBamfiRZT0GiK9qjv48eB1tJvVR41WFgLHWFwh9K9Ln/lc= 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 3/15/23 23:05, Lorenzo Stoakes wrote: > On Thu, Mar 09, 2023 at 12:12:57PM +0100, Vlastimil Babka wrote: >> --- a/mm/mmap.c >> +++ b/mm/mmap.c >> @@ -742,12 +742,13 @@ int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma, >> >> /* >> * If the vma has a ->close operation then the driver probably needs to release >> - * per-vma resources, so we don't attempt to merge those. >> + * per-vma resources, so we don't attempt to merge those in case the caller >> + * indicates the current vma may be removed as part of the merge. > > Nit: 'in case the caller indicates' -> 'if the caller indicates' Ok, -fix patch below. ... >> - if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name) && >> + if (is_mergeable_vma(vma, file, vm_flags, vm_userfaultfd_ctx, anon_name, false) && >> is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) { >> pgoff_t vm_pglen; >> vm_pglen = vma_pages(vma); >> -- >> 2.39.2 >> > > I wonder whether this might be moved later into the actual vma_merge() logic so > we only abort a merge at the point a VMA with ->close() would otherwise be > removed? But obviously that would probably need some further clean up to make it > not add yet more complexity to an already very complicated bit of logic. Yeah, can try that later to cover the remaining cases where ->close prevents merging unnecessarily. > Otherwise, very nice, clear + conservative so, > > Reviewed-By: Lorenzo Stoakes Thanks! ----8<---- >From b8072720288491bdc887ebebbb099babcfb108a5 Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Thu, 16 Mar 2023 11:54:27 +0100 Subject: [PATCH] mm/mmap: start distinguishing if vma can be removed in mergeability test-fix Adjust comment as suggested by Lorenzo. Signed-off-by: Vlastimil Babka --- mm/mmap.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/mmap.c b/mm/mmap.c index 4259095a2982..b255e6352710 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -742,8 +742,8 @@ int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma, /* * If the vma has a ->close operation then the driver probably needs to release - * per-vma resources, so we don't attempt to merge those in case the caller - * indicates the current vma may be removed as part of the merge. + * per-vma resources, so we don't attempt to merge those if the caller indicates + * the current vma may be removed as part of the merge. */ static inline bool is_mergeable_vma(struct vm_area_struct *vma, struct file *file, unsigned long vm_flags, -- 2.39.2