From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f50.google.com (mail-pa0-f50.google.com [209.85.220.50]) by kanga.kvack.org (Postfix) with ESMTP id 59B8D82966 for ; Fri, 11 Apr 2014 16:21:42 -0400 (EDT) Received: by mail-pa0-f50.google.com with SMTP id kq14so5867202pab.9 for ; Fri, 11 Apr 2014 13:21:41 -0700 (PDT) Received: from mga09.intel.com (mga09.intel.com. [134.134.136.24]) by mx.google.com with ESMTP id pu9si4844452pbb.405.2014.04.11.13.21.41 for ; Fri, 11 Apr 2014 13:21:41 -0700 (PDT) Subject: [PATCH] mm: pass VM_BUG_ON() reason to dump_page() From: Dave Hansen Date: Fri, 11 Apr 2014 13:21:25 -0700 Message-Id: <20140411202125.01D1D100@viggo.jf.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Dave Hansen From: Dave Hansen I recently added a patch to let folks pass a "reason" string dump_page() which gets dumped out along with the page's data. This essentially saves the bug-reader a trip in to the source to figure out why we BUG_ON()'d. The new VM_BUG_ON_PAGE() passes in NULL for "reason". It seems like we might as well pass the BUG_ON() condition if we have it. This will bloat kernels a bit with ~160 new strings, but this is all under a debugging option anyway. page:ffffea0008560280 count:1 mapcount:0 mapping:(null) index:0x0 page flags: 0xbfffc0000000001(locked) page dumped because: VM_BUG_ON_PAGE(PageLocked(page)) ------------[ cut here ]------------ kernel BUG at /home/davehans/linux.git/mm/filemap.c:464! invalid opcode: 0000 [#1] SMP CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.14.0+ #251 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 ... Signed-off-by: Dave Hansen --- b/include/linux/mmdebug.h | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff -puN include/linux/mmdebug.h~pass-VM_BUG_ON-reason-to-dump_page include/linux/mmdebug.h --- a/include/linux/mmdebug.h~pass-VM_BUG_ON-reason-to-dump_page 2014-04-11 11:20:37.175240200 -0700 +++ b/include/linux/mmdebug.h 2014-04-11 13:11:09.498620420 -0700 @@ -9,8 +9,13 @@ extern void dump_page_badflags(struct pa #ifdef CONFIG_DEBUG_VM #define VM_BUG_ON(cond) BUG_ON(cond) -#define VM_BUG_ON_PAGE(cond, page) \ - do { if (unlikely(cond)) { dump_page(page, NULL); BUG(); } } while (0) +#define VM_BUG_ON_PAGE(cond, page) \ + do { \ + if (unlikely(cond)) { \ + dump_page(page, "VM_BUG_ON_PAGE(" __stringify(cond)")");\ + BUG(); \ + } \ + } while (0) #else #define VM_BUG_ON(cond) BUILD_BUG_ON_INVALID(cond) #define VM_BUG_ON_PAGE(cond, page) VM_BUG_ON(cond) _ -- 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/ . Don't email: email@kvack.org