From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx158.postini.com [74.125.245.158]) by kanga.kvack.org (Postfix) with SMTP id DC4A66B004D for ; Wed, 2 May 2012 00:28:36 -0400 (EDT) From: Minchan Kim Subject: [PATCH] vmalloc: add warning in __vmalloc Date: Wed, 2 May 2012 13:28:09 +0900 Message-Id: <1335932890-25294-1-git-send-email-minchan@kernel.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kosaki.motohiro@gmail.com, rientjes@google.com, Minchan Kim , Neil Brown , Artem Bityutskiy , David Woodhouse , Theodore Ts'o , Adrian Hunter , Steven Whitehouse , "David S. Miller" , James Morris , Alexander Viro , Sage Weil 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 Cc: Artem Bityutskiy Cc: David Woodhouse Cc: "Theodore Ts'o" Cc: Adrian Hunter Cc: Steven Whitehouse Cc: "David S. Miller" Cc: James Morris Cc: Alexander Viro Cc: Sage Weil Signed-off-by: Minchan Kim --- 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org