Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752069Ab2EBE2i (ORCPT ); Wed, 2 May 2012 00:28:38 -0400 Received: from LGEMRELSE1Q.lge.com ([156.147.1.111]:60885 "EHLO LGEMRELSE1Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751229Ab2EBE2h (ORCPT ); Wed, 2 May 2012 00:28:37 -0400 X-AuditID: 9c93016f-b7b1bae0000044da-7f-4fa0b7ed5194 From: Minchan Kim 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 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> X-Mailer: git-send-email 1.7.9.5 X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2420 Lines: 66 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 from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/