Commit de55be42 authored Jul 28, 2025 by Kairui Song Committed by Andrew Morton Aug 02, 2025

mm/shmem, swap: fix major fault counting

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.

Link: https://lkml.kernel.org/r/20250728075306.12704-9-ryncsn@gmail.com


Signed-off-by: Kairui Song <kasong@tencent.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chris Li <chrisl@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

parent 93c0476e

mm/shmem.c

+5 −7

Original line number	Diff line number	Diff line
		@@ -2356,13 +2356,6 @@ 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 swapin skipping swap cache & readahead */
		folio = shmem_swap_alloc_folio(inode, vma, index,
		@@ -2381,6 +2374,11 @@ static int shmem_swapin_folio(struct inode *inode, pgoff_t index,
		goto failed;
		}
		}
		if (fault_type) {
		*fault_type \|= VM_FAULT_MAJOR;
		count_vm_event(PGMAJFAULT);
		count_memcg_event_mm(fault_mm, PGMAJFAULT);
		}
		}

		if (order > folio_order(folio)) {