From: Peter Xu <peterx@xxxxxxxxxx> Subject: mm/smaps: simplify shmem handling of pte holes Firstly, check_shmem_swap variable is actually not necessary, because it's always set with pte_hole hook; checking each would work. Meanwhile, the check within smaps_pte_entry is not easy to follow. E.g., pte_none() check is not needed as "!pte_present && !is_swap_pte" is the same. Since at it, use the pte_hole() helper rather than dup the page cache lookup. Still keep the CONFIG_SHMEM part so the code can be optimized to nop for !SHMEM. There will be a very slight functional change in smaps_pte_entry(), that for !SHMEM we'll return early for pte_none (before checking page==NULL), but that's even nicer. Link: https://lkml.kernel.org/r/20210917164756.8586-4-peterx@xxxxxxxxxx Signed-off-by: Peter Xu <peterx@xxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/proc/task_mmu.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) --- a/fs/proc/task_mmu.c~mm-smaps-simplify-shmem-handling-of-pte-holes +++ a/fs/proc/task_mmu.c @@ -397,7 +397,6 @@ struct mem_size_stats { u64 pss_shmem; u64 pss_locked; u64 swap_pss; - bool check_shmem_swap; }; static void smaps_page_accumulate(struct mem_size_stats *mss, @@ -490,6 +489,16 @@ static int smaps_pte_hole(unsigned long #define smaps_pte_hole NULL #endif /* CONFIG_SHMEM */ +static void smaps_pte_hole_lookup(unsigned long addr, struct mm_walk *walk) +{ +#ifdef CONFIG_SHMEM + if (walk->ops->pte_hole) { + /* depth is not used */ + smaps_pte_hole(addr, addr + PAGE_SIZE, 0, walk); + } +#endif +} + static void smaps_pte_entry(pte_t *pte, unsigned long addr, struct mm_walk *walk) { @@ -518,12 +527,8 @@ static void smaps_pte_entry(pte_t *pte, } } else if (is_pfn_swap_entry(swpent)) page = pfn_swap_entry_to_page(swpent); - } else if (unlikely(IS_ENABLED(CONFIG_SHMEM) && mss->check_shmem_swap - && pte_none(*pte))) { - page = xa_load(&vma->vm_file->f_mapping->i_pages, - linear_page_index(vma, addr)); - if (xa_is_value(page)) - mss->swap += PAGE_SIZE; + } else { + smaps_pte_hole_lookup(addr, walk); return; } @@ -737,8 +742,6 @@ static void smap_gather_stats(struct vm_ return; #ifdef CONFIG_SHMEM - /* In case of smaps_rollup, reset the value from previous vma */ - mss->check_shmem_swap = false; if (vma->vm_file && shmem_mapping(vma->vm_file->f_mapping)) { /* * For shared or readonly shmem mappings we know that all @@ -756,7 +759,6 @@ static void smap_gather_stats(struct vm_ !(vma->vm_flags & VM_WRITE))) { mss->swap += shmem_swapped; } else { - mss->check_shmem_swap = true; ops = &smaps_shmem_walk_ops; } } _
