Following on from Vlastimil Babka's patch series "cleanup vma_merge() and improve mergeability tests" which was in turn based on Liam's prior cleanups, this patch series introduces changes discussed in review of Vlastimil's series and goes further in attempting to make the logic as clear as possible. Nearly all of this should have absolutely no functional impact, however it does add a singular VM_WARN_ON() case. With many thanks to Vernon for helping kick start the discussion around simplification - abstract use of vma did indeed turn out not to be necessary, Liam for his excellent suggestions which greatly simplified things, and Vlastimil for his careful review and feedback. v5: - Fixup typo. - Fix email client snafu with duplicate cover letter. v4: - Mention 'A' -> '*' in commit message. - Various small nits. https://lore.kernel.org/all/cover.1679515236.git.lstoakes@xxxxxxxxx v3: - Combine vma_lookup() cases and reinsert accidentally excluded next = NULL assignment. - Reword commit messages to more correctly reflect the current changes. - Avoid multiple assignment to prev, take vma_start, vma_pgoff assignment out of the local variable declarations and revert to setting in if (prev) block. https://lore.kernel.org/all/cover.1679468982.git.lstoakes@xxxxxxxxx v2: - Put the patch series on a serious diet, cut comments down to avoid bloat. - Added clever use of find_vma_intersection() and vma_lookup() as suggested by Liam which improved clarity + brevity significantly. - Eliminated the use of a temporary vma local as suggested by Vernon, it does seem this was ultimately adding confusion and Liam's suggestions eliminated the need for this. - Moved around initial variables to be more sensible and to initialise each variable in one place where possible. https://lore.kernel.org/all/cover.1679431180.git.lstoakes@xxxxxxxxx v1: https://lore.kernel.org/all/cover.1679137163.git.lstoakes@xxxxxxxxx Lorenzo Stoakes (4): mm/mmap/vma_merge: further improve prev/next VMA naming mm/mmap/vma_merge: fold curr, next assignment logic mm/mmap/vma_merge: explicitly assign res, vma, extend invariants mm/mmap/vma_merge: init cleanup, be explicit about the non-mergeable case mm/mmap.c | 138 ++++++++++++++++++++++++++++-------------------------- 1 file changed, 71 insertions(+), 67 deletions(-) -- 2.39.2
