From a2e740e216f5bf49ccb83b6d490c72a340558a43 Mon Sep 17 00:00:00 2001 From: "Matthew Wilcox (Oracle)" Date: Wed, 11 Dec 2024 20:25:37 +0000 Subject: [PATCH] vmalloc: fix accounting with i915 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 --- mm/vmalloc.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index f009b21705c163..5c88d0e90c209a 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -3374,7 +3374,8 @@ void vfree(const void *addr) struct page *page = vm->pages[i]; BUG_ON(!page); - mod_memcg_page_state(page, MEMCG_VMALLOC, -1); + if (!(vm->flags & VM_MAP_PUT_PAGES)) + mod_memcg_page_state(page, MEMCG_VMALLOC, -1); /* * High-order allocs for huge vmallocs are split, so * can be freed as an array of order-0 allocations @@ -3382,7 +3383,8 @@ void vfree(const void *addr) __free_page(page); cond_resched(); } - atomic_long_sub(vm->nr_pages, &nr_vmalloc_pages); + if (!(vm->flags & VM_MAP_PUT_PAGES)) + atomic_long_sub(vm->nr_pages, &nr_vmalloc_pages); kvfree(vm->pages); kfree(vm); }