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charset=us-ascii Content-Disposition: inline In-Reply-To: <3b565157-9a9b-47da-a0b9-11a4e318de44@lucifer.local> User-Agent: NeoMutt/20170113 (1.7.2) X-Rspamd-Queue-Id: 0CA71A0024 X-Stat-Signature: ft6gwhkgqo3xankm67i68peb3ihn9w9w X-Rspamd-Server: rspam09 X-Rspam-User: X-HE-Tag: 1729761709-152098 X-HE-Meta: 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 59B1K2Dq 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 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: List-Subscribe: List-Unsubscribe: On Thu, Oct 24, 2024 at 10:18:33AM +0100, Lorenzo Stoakes wrote: >On Thu, Oct 24, 2024 at 09:10:12AM +0000, Wei Yang wrote: >> On Thu, Oct 24, 2024 at 10:03:34AM +0100, Lorenzo Stoakes wrote: >> >On Thu, Oct 24, 2024 at 08:42:22AM +0000, Wei Yang wrote: >> >> can_merge_right implies can_vma_merge_right() has checked the pgoff. >> >> >> >> Don't need to assign it again. >> > >> >Would prefer a bigger commit message something like: >> > >> >By this point can_vma_merge_right() must have returned true, which implies >> >can_vma_merge_before() also returned true, which already asserts that the >> >pgoff is as expected for a merge with the following VMA, thus this >> >assignment is redundant. >> > >> >> Will change to this in next version. > >Thanks. The actual change itself looks good! > >> >> >> >> >> Signed-off-by: Wei Yang >> > >> >Reviewed-by: Lorenzo Stoakes >> > >> >> CC: Lorenzo Stoakes >> >> --- >> >> mm/vma.c | 2 -- >> >> 1 file changed, 2 deletions(-) >> >> >> >> diff --git a/mm/vma.c b/mm/vma.c >> >> index 4737afcb064c..fb4f1863f88e 100644 >> >> --- a/mm/vma.c >> >> +++ b/mm/vma.c >> >> @@ -915,7 +915,6 @@ struct vm_area_struct *vma_merge_new_range(struct vma_merge_struct *vmg) >> >> unsigned long start = vmg->start; >> >> unsigned long end = vmg->end; >> >> pgoff_t pgoff = vmg->pgoff; >> >> - pgoff_t pglen = PHYS_PFN(end - start); >> >> bool can_merge_left, can_merge_right; >> >> >> >> mmap_assert_write_locked(vmg->mm); >> >> @@ -936,7 +935,6 @@ struct vm_area_struct *vma_merge_new_range(struct vma_merge_struct *vmg) >> >> if (can_merge_right) { >> >> vmg->end = next->vm_end; >> >> vmg->vma = next; >> >> - vmg->pgoff = next->vm_pgoff - pglen; >> >> } >> >> >> >> /* If we can merge with the previous VMA, adjust vmg accordingly. */ >> >> -- >> >> 2.34.1 >> >> >> >> >> > >> >Thanks, nice spot! >> > >> >For the purposes of explaining it on-list this is because: >> > >> >static bool can_vma_merge_right(struct vma_merge_struct *vmg, >> > bool can_merge_left) >> >{ >> > if (!vmg->next || vmg->end != vmg->next->vm_start || >> > !can_vma_merge_before(vmg)) >> > return false; >> > ... >> >} >> > >> >And: >> > >> >static bool can_vma_merge_before(struct vma_merge_struct *vmg) >> >{ >> > pgoff_t pglen = PHYS_PFN(vmg->end - vmg->start); >> >... >> > if (vmg->next->vm_pgoff == vmg->pgoff + pglen) >> > return true; >> >... >> >} >> > >> >Which implies vmg->pgoff == vmg->next->vm_pgoff - pglen. >> > >> >None of these values are changed between the check and prior assignment, so >> >this was an entirely redundant assignment. >> >> Do you suggest me to add this in change log? > >Sure, I am a big believer in putting as much detail as possible in commit >messages, we definitely need to explain why we're doing this to future >observers (including me... ;) > Sure, will arrange to put these in change log too. >> >> -- >> Wei Yang >> Help you, Help me >> -- Wei Yang Help you, Help me