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charset="UTF-8" X-Stat-Signature: 3mrmpm1fhdancmy4txej3edqdso9fyda X-Rspam-User: X-Rspamd-Queue-Id: 6A2394000E X-Rspamd-Server: rspam03 X-HE-Tag: 1789745608-549397 X-HE-Meta: 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 6nweMPvg 1efL2GLkXWq6WyhL0vFqGz6FYYvRvYwCllDtAXprhYAD5dC6qu+nYqPfoMjYXVjNmukvxH1RJnX2p20m6sHxDGg57+nyHDeefLoFS3uS7PPwDwkx2WXDr5iu7NXuuYAZH7W47VjE7ESceEpV42x+9XKWcgBhK7efDMLqjM0laHTw99S41FyAoV+IWWamxLOZ8qjDVzl8xs93b4Ffn/RWJqu/tRdShm+HkVts9h3RrDXWuwEKdYNzx8BLo8wZ38VB1MRGxHfS2svWPGXTXmp/5C7H7QOZlSzlaLxeTGHJe/GMhTX1mdC/q4DYsD1bxtn4BfVxYcdMRX6cRN+6hkX8mqdu61g7eP+VkhuTV1vKFqVziXkt2PoZ7GxvHigjIuLQDGv5l9Edfk9Zwfrj7evvUCoQcZytM+s0Wfeoc/EVpmMJZWw31nQPFnp7v96LKGksyxQfh9sgkMTf3wZwSLGDJPBGpVWzfRJRiuPILT7a8/wxKHaAX0+i3AvYxVxfgzj7L0cZdUHXJ7/hezQ6h98UlbN6FK2JvSv9qOwARes+R5trQnpSE+SmSsRhHcX2YiKKAqcCK2K7zhZObsT+QsyF1WfUbpPM2W7129Wabqc5csPQ1VJVHuj2mZI0Y4ftTexVa1AiQs5MBKfK1fDTn/8jycKa1tgbOSrk+cl7FsokTKcUWVU6iLjjqtmJJIw== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: smap_gather_stats() optimizes stats gathering by skipping the walk for shmem mappings in certain conditions. Update the comment to clarify these conditions and use vma_is_cow_mapping() for CoW identification instead of open-coding it. No functional change intended. Suggested by: David Hildenbrand (Arm) Signed-off-by: Suren Baghdasaryan Reviewed-by: Lorenzo Stoakes (ARM) Acked-by: David Hildenbrand (Arm) --- fs/proc/task_mmu.c | 23 +++++++++-------------- 1 file changed, 9 insertions(+), 14 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 8a72dc0dc945..f1ce15981253 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -1274,23 +1274,18 @@ static void smap_gather_stats(struct proc_maps_private *priv, if (vma->vm_file && shmem_mapping(vma->vm_file->f_mapping)) { /* - * For shared or readonly shmem mappings we know that all - * swapped out pages belong to the shmem object, and we can - * obtain the swap value much more efficiently. For private - * writable mappings, we might have COW pages that are - * not affected by the parent swapped out pages of the shmem - * object, so we have to distinguish them during the page walk. - * Unless we know that the shmem object (or the part mapped by - * our VMA) has no swapped out pages at all. + * CoW mappings might map anon folios that do not belong to + * shmem. Perform a less efficient page table walk in this + * situation, unless we know that the shmem object (or the + * part mapped by our VMA) has no swapped out pages at all. */ - unsigned long shmem_swapped = shmem_swap_usage(vma); + const unsigned long shmem_swapped = shmem_swap_usage(vma); + const bool is_cow = vma_is_cow_mapping(vma); - if (!start && (!shmem_swapped || (vma->vm_flags & VM_SHARED) || - !(vma->vm_flags & VM_WRITE))) { - mss->swap += shmem_swapped; - } else { + if (start || (shmem_swapped && is_cow)) ops = get_smaps_shmem_walk_ops(priv); - } + else + mss->swap += shmem_swapped; } if (!start) -- 2.55.0.1082.g2b9226bbc0-goog