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authorHugh Dickins <hughd@google.com>2024-12-04 22:50:06 -0800
committerAndrew Morton <akpm@linux-foundation.org>2024-12-18 19:04:42 -0800
commitdad2dc9c92e0f93f33cebcb0595b8daa3d57473f (patch)
tree77caa0b70d498d1a13b936257195aafb98d97e40
parent7782e3b3b004e8cb94a88621a22cc3c2f33e5b90 (diff)
downloadlwn-dad2dc9c92e0f93f33cebcb0595b8daa3d57473f.tar.gz
lwn-dad2dc9c92e0f93f33cebcb0595b8daa3d57473f.zip
mm: shmem: fix ShmemHugePages at swapout
/proc/meminfo ShmemHugePages has been showing overlarge amounts (more than Shmem) after swapping out THPs: we forgot to update NR_SHMEM_THPS. Add shmem_update_stats(), to avoid repetition, and risk of making that mistake again: the call from shmem_delete_from_page_cache() is the bugfix; the call from shmem_replace_folio() is reassuring, but not really a bugfix (replace corrects misplaced swapin readahead, but huge swapin readahead would be a mistake). Link: https://lkml.kernel.org/r/5ba477c8-a569-70b5-923e-09ab221af45b@google.com Fixes: 809bc86517cc ("mm: shmem: support large folio swap out") Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev> Reviewed-by: Yosry Ahmed <yosryahmed@google.com> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
-rw-r--r--mm/shmem.c22
1 files changed, 12 insertions, 10 deletions
diff --git a/mm/shmem.c b/mm/shmem.c
index ccb9629a0f70..f6fb053ac50d 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -787,6 +787,14 @@ static bool shmem_huge_global_enabled(struct inode *inode, pgoff_t index,
}
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+static void shmem_update_stats(struct folio *folio, int nr_pages)
+{
+ if (folio_test_pmd_mappable(folio))
+ __lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, nr_pages);
+ __lruvec_stat_mod_folio(folio, NR_FILE_PAGES, nr_pages);
+ __lruvec_stat_mod_folio(folio, NR_SHMEM, nr_pages);
+}
+
/*
* Somewhat like filemap_add_folio, but error if expected item has gone.
*/
@@ -821,10 +829,7 @@ static int shmem_add_to_page_cache(struct folio *folio,
xas_store(&xas, folio);
if (xas_error(&xas))
goto unlock;
- if (folio_test_pmd_mappable(folio))
- __lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, nr);
- __lruvec_stat_mod_folio(folio, NR_FILE_PAGES, nr);
- __lruvec_stat_mod_folio(folio, NR_SHMEM, nr);
+ shmem_update_stats(folio, nr);
mapping->nrpages += nr;
unlock:
xas_unlock_irq(&xas);
@@ -852,8 +857,7 @@ static void shmem_delete_from_page_cache(struct folio *folio, void *radswap)
error = shmem_replace_entry(mapping, folio->index, folio, radswap);
folio->mapping = NULL;
mapping->nrpages -= nr;
- __lruvec_stat_mod_folio(folio, NR_FILE_PAGES, -nr);
- __lruvec_stat_mod_folio(folio, NR_SHMEM, -nr);
+ shmem_update_stats(folio, -nr);
xa_unlock_irq(&mapping->i_pages);
folio_put_refs(folio, nr);
BUG_ON(error);
@@ -1969,10 +1973,8 @@ static int shmem_replace_folio(struct folio **foliop, gfp_t gfp,
}
if (!error) {
mem_cgroup_replace_folio(old, new);
- __lruvec_stat_mod_folio(new, NR_FILE_PAGES, nr_pages);
- __lruvec_stat_mod_folio(new, NR_SHMEM, nr_pages);
- __lruvec_stat_mod_folio(old, NR_FILE_PAGES, -nr_pages);
- __lruvec_stat_mod_folio(old, NR_SHMEM, -nr_pages);
+ shmem_update_stats(new, nr_pages);
+ shmem_update_stats(old, -nr_pages);
}
xa_unlock_irq(&swap_mapping->i_pages);