From: Luis Chamberlain Date: Thu, 9 Mar 2023 23:05:43 +0000 (-0800) Subject: shmem: skip page split if we're not reclaiming X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=9a976f0c847b67d22ed694556a3626ed92da0422;p=users%2Fjedix%2Flinux-maple.git shmem: skip page split if we're not reclaiming In theory when info->flags & VM_LOCKED we should not be getting shem_writepage() called so we should be verifying this with a WARN_ON_ONCE(). Since we should not be swapping then best to ensure we also don't do the folio split earlier too. So just move the check early to avoid folio splits in case its a dubious call. We also have a similar early bail when !total_swap_pages so just move that earlier to avoid the possible folio split in the same situation. Link: https://lkml.kernel.org/r/20230309230545.2930737-5-mcgrof@kernel.org Signed-off-by: Luis Chamberlain Acked-by: David Hildenbrand Reviewed-by: Christian Brauner Reviewed-by: Yosry Ahmed Tested-by: Xin Hao Reviewed-by: Davidlohr Bueso Cc: Adam Manzanares Cc: Davidlohr Bueso Cc: Hugh Dickins Cc: Kees Cook Cc: Matthew Wilcox Cc: Pankaj Raghav Signed-off-by: Andrew Morton --- diff --git a/mm/shmem.c b/mm/shmem.c index b297eaf43f43..7751c136eadb 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1347,6 +1347,12 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) if (WARN_ON_ONCE(!wbc->for_reclaim)) goto redirty; + if (WARN_ON_ONCE(info->flags & VM_LOCKED)) + goto redirty; + + if (!total_swap_pages) + goto redirty; + /* * If /sys/kernel/mm/transparent_hugepage/shmem_enabled is "always" or * "force", drivers/gpu/drm/i915/gem/i915_gem_shmem.c gets huge pages, @@ -1362,10 +1368,6 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc) } index = folio->index; - if (info->flags & VM_LOCKED) - goto redirty; - if (!total_swap_pages) - goto redirty; /* * This is somewhat ridiculous, but without plumbing a SWAP_MAP_FALLOC