linux-kernel - Re: [PATCH] mm: kvfree the swap cluster info if the swap file is unsatisfactory

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Date:   Fri, 1 Sep 2017 01:33:53 -0700 (PDT)
From:   David Rientjes <rientjes@...gle.com>
To:     Andrew Morton <akpm@...ux-foundation.org>,
        "Darrick J. Wong" <darrick.wong@...cle.com>
cc:     ying.huang@...el.com, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: kvfree the swap cluster info if the swap file is
 unsatisfactory

On Thu, 31 Aug 2017, Darrick J. Wong wrote:

> If initializing a small swap file fails because the swap file has a
> problem (holes, etc.) then we need to free the cluster info as part of
> cleanup.  Unfortunately a previous patch changed the code to use
> kvzalloc but did not change all the vfree calls to use kvfree.
> 

Hopefully this can make it into 4.13.

Fixes: 54f180d3c181 ("mm, swap: use kvzalloc to allocate some swap data structures")
Cc: stable@...r.kernel.org [4.12]

> Found by running generic/357 from xfstests.
> 
> Signed-off-by: Darrick J. Wong <darrick.wong@...cle.com>

Acked-by: David Rientjes <rientjes@...gle.com>

But I think there's also a memory leak and we need this on top of your 
fix:


mm, swapfile: fix swapon frontswap_map memory leak on error 

Free frontswap_map if an error is encountered before enable_swap_info().

Signed-off-by: David Rientjes <rientjes@...gle.com>
---
 mm/swapfile.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mm/swapfile.c b/mm/swapfile.c
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -3053,6 +3053,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 	spin_unlock(&swap_lock);
 	vfree(swap_map);
 	kvfree(cluster_info);
+	kvfree(frontswap_map);
 	if (swap_file) {
 		if (inode && S_ISREG(inode->i_mode)) {
 			inode_unlock(inode);