linux-kernel - [PATCHv2] mm/page_owner: use kvmalloc instead of kmalloc

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Message-ID: <1540779403-27622-1-git-send-email-miles.chen@mediatek.com>
Date:   Mon, 29 Oct 2018 10:16:43 +0800
From:   <miles.chen@...iatek.com>
To:     Matthias Brugger <matthias.bgg@...il.com>
CC:     <linux-kernel@...r.kernel.org>, <linux-mm@...ck.org>,
        <wsd_upstream@...iatek.com>, <linux-mediatek@...ts.infradead.org>,
        <linux-arm-kernel@...ts.infradead.org>,
        Joe Perches <joe@...ches.com>,
        Michal Hocko <mhocko@...nel.org>,
        Matthew Wilcox <willy@...radead.org>,
        Miles Chen <miles.chen@...iatek.com>
Subject: [PATCHv2] mm/page_owner: use kvmalloc instead of kmalloc

From: Miles Chen <miles.chen@...iatek.com>

The kbuf used by page owner is allocated by kmalloc(), which means it
can use only normal memory and there might be a "out of memory"
issue when we're out of normal memory.

Use kvmalloc() so we can also allocate kbuf from
normal/hihghmem on 32bit kernel.

Clamp the kbuf size to PAGE_SIZE.

Change since v1:
  - use kvmalloc()
  - clamp buffer size to PAGE_SIZE

Signed-off-by: Miles Chen <miles.chen@...iatek.com>
Cc: Joe Perches <joe@...ches.com>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: Michal Hocko <mhocko@...nel.org>
---
 mm/page_owner.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/mm/page_owner.c b/mm/page_owner.c
index d80adfe..a064cd0 100644
--- a/mm/page_owner.c
+++ b/mm/page_owner.c
@@ -1,7 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/debugfs.h>
 #include <linux/mm.h>
-#include <linux/slab.h>
 #include <linux/uaccess.h>
 #include <linux/bootmem.h>
 #include <linux/stacktrace.h>
@@ -351,7 +350,8 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m,
 		.skip = 0
 	};
 
-	kbuf = kmalloc(count, GFP_KERNEL);
+	count = count > PAGE_SIZE ? PAGE_SIZE : count;
+	kbuf = kvmalloc(count, GFP_KERNEL);
 	if (!kbuf)
 		return -ENOMEM;
 
@@ -397,11 +397,11 @@ void pagetypeinfo_showmixedcount_print(struct seq_file *m,
 	if (copy_to_user(buf, kbuf, ret))
 		ret = -EFAULT;
 
-	kfree(kbuf);
+	kvfree(kbuf);
 	return ret;
 
 err:
-	kfree(kbuf);
+	kvfree(kbuf);
 	return -ENOMEM;
 }
 
-- 
1.9.1