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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@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Peter Xu 2021-11-05 13:36:05 -07:00 committed by Linus Torvalds
parent 02399c8802
commit 2301003215
1 changed files with 12 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

22
fs/proc/task_mmu.c
View File

@ -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 addr, unsigned long end,
#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, unsigned long addr,
}
} 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_area_struct *vma,
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_area_struct *vma,
!(vma->vm_flags & VM_WRITE))) {
mss->swap += shmem_swapped;
} else {
mss->check_shmem_swap = true;
ops = &smaps_shmem_walk_ops;
}
}