On 2025/6/27 14:20, Kairui Song wrote:
> From: Kairui Song <kasong@tencent.com>
>
> If the swapin failed, don't update the major fault count. There is a
> long existing comment for doing it this way, now with previous cleanups,
> we can finally fix it.
Sounds reasonable to me. Additionally, swapin failure is a rare event,
so I think this patch will have little impact on user statistics.
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> Signed-off-by: Kairui Song <kasong@tencent.com>
> ---
> mm/shmem.c | 11 +++++------
> 1 file changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/mm/shmem.c b/mm/shmem.c
> index 5f2641fd1be7..ea9a105ded5d 100644
> --- a/mm/shmem.c
> +++ b/mm/shmem.c
> @@ -2316,12 +2316,6 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
> /* Look it up and read it in.. */
> folio = swap_cache_get_folio(swap, NULL, 0);
> if (!folio) {
> - /* Or update major stats only when swapin succeeds?? */
> - if (fault_type) {
> - *fault_type |= VM_FAULT_MAJOR;
> - count_vm_event(PGMAJFAULT);
> - count_memcg_event_mm(fault_mm, PGMAJFAULT);
> - }
> if (data_race(si->flags & SWP_SYNCHRONOUS_IO)) {
> /* Direct mTHP swapin without swap cache or readahead */
> folio = shmem_swapin_direct(inode, vma, index,
> @@ -2341,6 +2335,11 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
> }
> if (!folio)
> goto failed;
> + if (fault_type) {
> + *fault_type |= VM_FAULT_MAJOR;
> + count_vm_event(PGMAJFAULT);
> + count_memcg_event_mm(fault_mm, PGMAJFAULT);
> + }
> }
> /*
> * We need to split an existing large entry if swapin brought in a