linux-kernel - [PATCH] parisc: mm: Fix a memory leak related to pmd not attached to the pgd

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Date:	Mon, 13 Jul 2015 11:32:43 +0200
From:	Christophe JAILLET <christophe.jaillet@...adoo.fr>
To:	jejb@...isc-linux.org, deller@....de, mpatocka@...hat.com,
	kirill.shutemov@...ux.intel.com
Cc:	linux-parisc@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org,
	Christophe JAILLET <christophe.jaillet@...adoo.fr>
Subject: [PATCH] parisc: mm: Fix a memory leak related to pmd not attached to the pgd

Commit 0e0da48dee8d ("parisc: mm: don't count preallocated pmds")
introduced a memory leak.

After this commit, the 'return' statement in pmd_free is executed in all
cases. Even for pmd that are not attached to the pgd.
So 'free_pages' can never be called anymore, leading to a memory leak.

Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
---
This patch is *untested* as I don't have the hardware to test it.

This is just a guess based on the indentation, the comment in the code
and the commit log.
---
 arch/parisc/include/asm/pgalloc.h | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/parisc/include/asm/pgalloc.h b/arch/parisc/include/asm/pgalloc.h
index 3a08eae..f66d3738 100644
--- a/arch/parisc/include/asm/pgalloc.h
+++ b/arch/parisc/include/asm/pgalloc.h
@@ -72,7 +72,7 @@ static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long address)
 
 static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
 {
-	if(pmd_flag(*pmd) & PxD_FLAG_ATTACHED)
+	if (pmd_flag(*pmd) & PxD_FLAG_ATTACHED) {
 		/*
 		 * This is the permanent pmd attached to the pgd;
 		 * cannot free it.
@@ -81,6 +81,7 @@ static inline void pmd_free(struct mm_struct *mm, pmd_t *pmd)
 		 */
 		mm_inc_nr_pmds(mm);
 		return;
+	}
 	free_pages((unsigned long)pmd, PMD_ORDER);
 }
 
-- 
2.1.4

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