5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> [ 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@xxxxxxxxxxxxx Fixes: b944afc9d64d ("mm: add a VM_MAP_PUT_PAGES flag for vmap") Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx> Reviewed-by: Shakeel Butt <shakeel.butt@xxxxxxxxx> Reviewed-by: Balbir Singh <balbirs@xxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Cc: Christoph Hellwig <hch@xxxxxx> Cc: Muchun Song <muchun.song@xxxxxxxxx> Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx> Cc: "Uladzislau Rezki (Sony)" <urezki@xxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- mm/vmalloc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index cd434f0ec47f..3cb1f59d1b53 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2621,7 +2621,8 @@ static void __vunmap(const void *addr, int deallocate_pages) __free_pages(page, page_order); cond_resched(); } - 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); } -- 2.39.5
