| Message ID | 5ba477c8-a569-70b5-923e-09ab221af45b@google.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [hotfix] mm: shmem: fix ShmemHugePages at swapout | expand |
On Wed, Dec 04, 2024 at 10:50:06PM -0800, Hugh Dickins wrote: > /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). > > Fixes: 809bc86517cc ("mm: shmem: support large folio swap out") > Signed-off-by: Hugh Dickins <hughd@google.com> > Cc: stable@vger.kernel.org Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
On Wed, Dec 4, 2024 at 10:50 PM Hugh Dickins <hughd@google.com> wrote: > > /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). > > Fixes: 809bc86517cc ("mm: shmem: support large folio swap out") > Signed-off-by: Hugh Dickins <hughd@google.com> Reviewed-by: Yosry Ahmed <yosryahmed@google.com> > Cc: stable@vger.kernel.org > --- > mm/shmem.c | 22 ++++++++++++---------- > 1 file 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); > > -- > 2.43.0 >
On 2024/12/5 14:50, Hugh Dickins wrote: > /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). > > Fixes: 809bc86517cc ("mm: shmem: support large folio swap out") > Signed-off-by: Hugh Dickins <hughd@google.com> > Cc: stable@vger.kernel.org Indeed. Thanks for fixing. Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com> Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com> > --- > mm/shmem.c | 22 ++++++++++++---------- > 1 file 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); >
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);
/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). Fixes: 809bc86517cc ("mm: shmem: support large folio swap out") Signed-off-by: Hugh Dickins <hughd@google.com> Cc: stable@vger.kernel.org --- mm/shmem.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-)