From 461091c27f55bda99d05d30f7dc920302bf8b7a1 Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" Date: Mon, 23 Dec 2024 20:18:00 +0000 Subject: [PATCH] vmalloc: fix accounting with i915 [ Upstream commit a2e740e216f5bf49ccb83b6d490c72a340558a43 ] If the caller of vmap() specifies VM_MAP_PUT_PAGES (currently only the i915 driver), we will decrement nr_vmalloc_pages and MEMCG_VMALLOC in vfree(). These counters are incremented by vmalloc() but not by vmap() so this will cause an underflow. Check the VM_MAP_PUT_PAGES flag before decrementing either counter. Link: https://lkml.kernel.org/r/20241211202538.168311-1-willy@infradead.org Fixes: b944afc9d64d ("mm: add a VM_MAP_PUT_PAGES flag for vmap") Signed-off-by: Matthew Wilcox (Oracle) Acked-by: Johannes Weiner Reviewed-by: Shakeel Butt Reviewed-by: Balbir Singh Acked-by: Michal Hocko Cc: Christoph Hellwig Cc: Muchun Song Cc: Roman Gushchin Cc: "Uladzislau Rezki (Sony)" Cc: Signed-off-by: Andrew Morton Signed-off-by: Matthew Wilcox (Oracle) Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- mm/vmalloc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index d6a4794fa8ca8..fd1c8f51aa530 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2269,7 +2269,8 @@ static void __vunmap(const void *addr, int deallocate_pages) BUG_ON(!page); __free_pages(page, 0); } - atomic_long_sub(area->nr_pages, &nr_vmalloc_pages); + if (!(area->flags & VM_MAP_PUT_PAGES)) + atomic_long_sub(area->nr_pages, &nr_vmalloc_pages); kvfree(area->pages); } -- 2.47.3