From 0410ef3dc1a6838907d889cc000591dad1a77900 Mon Sep 17 00:00:00 2001
From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Date: Mon, 23 Dec 2024 20:07:29 +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) <willy@infradead.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Balbir Singh <balbirs@nvidia.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
mm/vmalloc.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index a0b650f50faa3..7c6694514606e 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2709,7 +2709,8 @@ static void __vunmap(const void *addr, int deallocate_pages)
struct page *page = area->pages[i];
BUG_ON(!page);
- mod_memcg_page_state(page, MEMCG_VMALLOC, -1);
+ if (!(area->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
@@ -2717,7 +2718,8 @@ static void __vunmap(const void *addr, int deallocate_pages)
__free_pages(page, 0);
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);
}
--
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