From: Kemeng Shi Date: Thu, 22 May 2025 12:25:51 +0000 (+0800) Subject: mm: swap: move nr_swap_pages counter decrement from folio_alloc_swap() to swap_range_... X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4f78252da887ee7e9d1875dd6e07d9baa936c04f;p=thirdparty%2Fkernel%2Flinux.git mm: swap: move nr_swap_pages counter decrement from folio_alloc_swap() to swap_range_alloc() Patch series "Some randome fixes and cleanups to swapfile". Patch 0-3 are some random fixes. Patch 4 is a cleanup. More details can be found in respective patches. This patch (of 4): When folio_alloc_swap() encounters a failure in either mem_cgroup_try_charge_swap() or add_to_swap_cache(), nr_swap_pages counter is not decremented for allocated entry. However, the following put_swap_folio() will increase nr_swap_pages counter unpairly and lead to an imbalance. Move nr_swap_pages decrement from folio_alloc_swap() to swap_range_alloc() to pair the nr_swap_pages counting. Link: https://lkml.kernel.org/r/20250522122554.12209-1-shikemeng@huaweicloud.com Link: https://lkml.kernel.org/r/20250522122554.12209-2-shikemeng@huaweicloud.com Fixes: 0ff67f990bd4 ("mm, swap: remove swap slot cache") Signed-off-by: Kemeng Shi Reviewed-by: Kairui Song Reviewed-by: Baoquan He Cc: Johannes Weiner Cc: Signed-off-by: Andrew Morton --- diff --git a/mm/swapfile.c b/mm/swapfile.c index 68ce283e84be8..b8464373b7aef 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -1115,6 +1115,7 @@ static void swap_range_alloc(struct swap_info_struct *si, if (vm_swap_full()) schedule_work(&si->reclaim_work); } + atomic_long_sub(nr_entries, &nr_swap_pages); } static void swap_range_free(struct swap_info_struct *si, unsigned long offset, @@ -1313,7 +1314,6 @@ int folio_alloc_swap(struct folio *folio, gfp_t gfp) if (add_to_swap_cache(folio, entry, gfp | __GFP_NOMEMALLOC, NULL)) goto out_free; - atomic_long_sub(size, &nr_swap_pages); return 0; out_free: