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

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Message-Id: <1447341424-11466-1-git-send-email-jmarchan@redhat.com>
Date:	Thu, 12 Nov 2015 16:17:04 +0100
From:	"Jerome Marchand" <jmarchan@...hat.com>
To:	linux-mm@...ck.org, Andrey Ryabinin <ryabinin.a.a@...il.com>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH] 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.
This patch only decreases vm->size when VM_NO_GUARD isn't set.

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

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index d045634..1388c3d 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1443,7 +1443,8 @@ 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;
+		if (!(vm->flags & VM_NO_GUARD))
+			vm->size -= PAGE_SIZE;
 
 		return vm;
 	}
-- 
2.4.3

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