The patch titled Subject: mm/vma: the pgoff is correct if can_merge_right has been added to the -mm mm-unstable branch. Its filename is mm-vma-the-pgoff-is-correct-if-can_merge_right.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vma-the-pgoff-is-correct-if-can_merge_right.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Wei Yang <richard.weiyang@xxxxxxxxx> Subject: mm/vma: the pgoff is correct if can_merge_right Date: Thu, 24 Oct 2024 09:33:47 +0000 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. Below is a more detail explanation. Current definition of can_vma_merge_right() is: 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. [lorenzo: rephrase the change log] Link: https://lkml.kernel.org/r/20241024093347.18057-1-richard.weiyang@xxxxxxxxx Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@xxxxxxxxxx> Cc: Jann Horn <jannh@xxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/vma.c | 2 -- 1 file changed, 2 deletions(-) --- a/mm/vma.c~mm-vma-the-pgoff-is-correct-if-can_merge_right +++ a/mm/vma.c @@ -964,7 +964,6 @@ struct vm_area_struct *vma_merge_new_ran struct vm_area_struct *next = vmg->next; unsigned long start = vmg->start; unsigned long end = vmg->end; - pgoff_t pglen = PHYS_PFN(end - start); bool can_merge_left, can_merge_right; bool just_expand = vmg->merge_flags & VMG_FLAG_JUST_EXPAND; @@ -986,7 +985,6 @@ struct vm_area_struct *vma_merge_new_ran 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. */ _ Patches currently in -mm which might be from richard.weiyang@xxxxxxxxx are maple_tree-i-is-always-less-than-or-equal-to-mas_end.patch maple_tree-goto-complete-directly-on-a-pivot-of-0.patch maple_tree-remove-maple_big_nodeparent.patch maple_tree-memset-maple_big_node-as-a-whole.patch maple_tree-root-node-could-be-handled-by-p_slot-too.patch maple_tree-clear-request_count-for-new-allocated-one.patch maple_tree-total-is-not-changed-for-nomem_one-case.patch maple_tree-simplify-mas_push_node.patch maple_tree-calculate-new_end-when-needed.patch maple_tree-remove-sanity-check-from-mas_wr_slot_store.patch mm-vma-the-pgoff-is-correct-if-can_merge_right.patch