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vmalloc: fix accounting with i915

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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: b944afc9d6 ("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>
This commit is contained in:
Matthew Wilcox (Oracle) 2024-12-11 20:25:37 +00:00 committed by Andrew Morton
parent faeec8e23c
commit a2e740e216
1 changed files with 4 additions and 2 deletions
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6
mm/vmalloc.c
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@ -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);
}