linux-kernel - [PATCH V2] mm: vmalloc: don't remove inexistent guard hole in remove_vm

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Message-Id: <1447346238-29153-1-git-send-email-jmarchan@redhat.com>
Date:	Thu, 12 Nov 2015 17:37:18 +0100
From:	"Jerome Marchand" <jmarchan@...hat.com>
To:	linux-mm@...ck.org, Andrey Ryabinin <ryabinin.a.a@...il.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH V2] mm: vmalloc: don't remove inexistent guard hole in remove_vm_area()

Commit 71394fe50146 ("mm: vmalloc: add flag preventing guard hole
allocation") missed a spot. Currently remove_vm_area() decreases
vm->size to "remove" the guard hole page, even when it isn't present.
All but one users just free the vm_struct rigth away and never access
vm->size anyway.
Don't touch the size in remove_vm_area() and have __vunmap() use the
proper get_vm_area_size() helper.

Signed-off-by: Jerome Marchand <jmarchan@...hat.com>
---
 mm/vmalloc.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index d045634..8e3c9c5 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1443,7 +1443,6 @@ struct vm_struct *remove_vm_area(const void *addr)
 		vmap_debug_free_range(va->va_start, va->va_end);
 		kasan_free_shadow(vm);
 		free_unmap_vmap_area(va);
-		vm->size -= PAGE_SIZE;
 
 		return vm;
 	}
@@ -1468,8 +1467,8 @@ static void __vunmap(const void *addr, int deallocate_pages)
 		return;
 	}
 
-	debug_check_no_locks_freed(addr, area->size);
-	debug_check_no_obj_freed(addr, area->size);
+	debug_check_no_locks_freed(addr, get_vm_area_size(area));
+	debug_check_no_obj_freed(addr, get_vm_area_size(area));
 
 	if (deallocate_pages) {
 		int i;
-- 
2.4.3

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