From: Minchan Kim <minchan@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kosaki.motohiro@gmail.com, rientjes@google.com,
Minchan Kim <minchan@kernel.org>, Neil Brown <neilb@suse.de>,
Artem Bityutskiy <dedekind1@gmail.com>,
David Woodhouse <dwmw2@infradead.org>,
"Theodore Ts'o" <tytso@mit.edu>,
Adrian Hunter <adrian.hunter@intel.com>,
Steven Whitehouse <swhiteho@redhat.com>,
"David S. Miller" <davem@davemloft.net>,
James Morris <jmorris@namei.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Sage Weil <sage@newdream.net>
Subject: [PATCH] vmalloc: add warning in __vmalloc
Date: Wed, 2 May 2012 13:28:09 +0900 [thread overview]
Message-ID: <1335932890-25294-1-git-send-email-minchan@kernel.org> (raw)
Now there are several places to use __vmalloc with GFP_ATOMIC,
GFP_NOIO, GFP_NOFS but unfortunately __vmalloc calls map_vm_area
which calls alloc_pages with GFP_KERNEL to allocate page tables.
It means it's possible to happen deadlock.
I don't know why it doesn't have reported until now.
Firstly, I tried passing gfp_t to lower functions to support __vmalloc
with such flags but other mm guys don't want and decided that
all of caller should be fixed.
http://marc.info/?l=linux-kernel&m=133517143616544&w=2
To begin with, let's listen other's opinion whether they can fix it
by other approach without calling __vmalloc with such flags.
So this patch adds warning in __vmalloc_node_range to detect it and
to be fixed hopely. __vmalloc_node_range isn't random chocie because
all caller which has gfp_mask of map_vm_area use it through __vmalloc_area_node.
And __vmalloc_area_node is current static function and is called by only
__vmalloc_node_range. So warning in __vmalloc_node_range would cover all
vmalloc functions which have gfp_t argument.
I Cced related maintainers.
If I miss someone, please Cced them.
* Changelog
* Replace WARN_ON with WARN_ON_ONCE - by Andrew Morton, Nick Piggin.
Cc: Neil Brown <neilb@suse.de>
Cc: Artem Bityutskiy <dedekind1@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: James Morris <jmorris@namei.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Sage Weil <sage@newdream.net>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
mm/vmalloc.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index c28b0b9..def5943 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1648,6 +1648,10 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
void *addr;
unsigned long real_size = size;
+ WARN_ON_ONCE(!(gfp_mask & __GFP_WAIT) ||
+ !(gfp_mask & __GFP_IO) ||
+ !(gfp_mask & __GFP_FS));
+
size = PAGE_ALIGN(size);
if (!size || (size >> PAGE_SHIFT) > totalram_pages)
goto fail;
--
1.7.9.5
next reply other threads:[~2012-05-02 4:28 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-02 4:28 Minchan Kim [this message]
2012-05-02 19:46 ` [PATCH] vmalloc: add warning in __vmalloc Andrew Morton
2012-05-03 1:02 ` Minchan Kim
2012-05-03 5:46 ` Sage Weil
2012-05-03 6:30 ` Nick Piggin
2012-05-03 7:13 ` Artem Bityutskiy
2012-05-03 7:14 ` Nick Piggin
2012-05-03 13:48 ` Steven Whitehouse
2012-05-03 5:55 ` Artem Bityutskiy
2012-05-03 11:11 ` Artem Bityutskiy
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