From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f70.google.com (mail-pl0-f70.google.com [209.85.160.70]) by kanga.kvack.org (Postfix) with ESMTP id 1792F6B0007 for ; Fri, 3 Aug 2018 17:23:01 -0400 (EDT) Received: by mail-pl0-f70.google.com with SMTP id 90-v6so3913851pla.18 for ; Fri, 03 Aug 2018 14:23:01 -0700 (PDT) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id j9-v6sor1637479plt.45.2018.08.03.14.22.59 for (Google Transport Security); Fri, 03 Aug 2018 14:22:59 -0700 (PDT) Date: Fri, 3 Aug 2018 14:22:57 -0700 From: Guenter Roeck Subject: Re: [PATCH v3 2/2] slab: __GFP_ZERO is incompatible with a constructor Message-ID: <20180803212257.GA5922@roeck-us.net> References: <20180411060320.14458-1-willy@infradead.org> <20180411060320.14458-3-willy@infradead.org> <20180411192448.GD22494@bombadil.infradead.org> <20180411235652.GA28279@bombadil.infradead.org> <20180412142718.GA20398@bombadil.infradead.org> <20180412191322.GA21205@bombadil.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180412191322.GA21205@bombadil.infradead.org> Sender: owner-linux-mm@kvack.org List-ID: To: Matthew Wilcox Cc: Christopher Lameter , linux-mm@kvack.org, Matthew Wilcox , Pekka Enberg , David Rientjes , Joonsoo Kim , Andrew Morton , linux-kernel@vger.kernel.org, Jan Kara , Jeff Layton , Mel Gorman Hi, On Thu, Apr 12, 2018 at 12:13:22PM -0700, Matthew Wilcox wrote: > From: Matthew Wilcox > > __GFP_ZERO requests that the object be initialised to all-zeroes, > while the purpose of a constructor is to initialise an object to a > particular pattern. We cannot do both. Add a warning to catch any > users who mistakenly pass a __GFP_ZERO flag when allocating a slab with > a constructor. > > Fixes: d07dbea46405 ("Slab allocators: support __GFP_ZERO in all allocators") > Signed-off-by: Matthew Wilcox > Acked-by: Johannes Weiner > Acked-by: Vlastimil Babka > Acked-by: Michal Hocko Seen with v4.18-rc7-139-gef46808 and v4.18-rc7-178-g0b5b1f9a78b5 when booting sh4 images in qemu: ata1: PATA max PIO0 mmio cmd 0xb4001000 ctl 0xb400080c irq 107 physmap platform flash device: 02000001 at 00000000 WARNING: CPU: 0 PID: 926 at mm/slab.c:2666 cache_alloc_refill+0x8a/0x594 Modules linked in: CPU: 0 PID: 926 Comm: kworker/u2:2 Not tainted 4.18.0-rc7-00139-gef46808 #1 PC is at cache_alloc_refill+0x8a/0x594 PR is at kmem_cache_alloc+0x72/0xac PC : 8c0b1e06 SP : 8fad5ed8 SR : 400080f0 TEA : c0087fe0 R0 : 00008000 R1 : 006080c0 R2 : 006080c0 R3 : 8c01e110 R4 : 8f801a00 R5 : 00000000 R6 : 00000000 R7 : 00000000 R8 : 0000000c R9 : 006080c0 R10 : 8c48302c R11 : 8fae8e60 R12 : 8f802540 R13 : 8f801a00 R14 : 8c4f22e8 MACH: 00000085 MACL: 00000e00 GBR : 00000000 PR : 8c0b244e Call trace: [<(ptrval)>] arch_local_irq_restore+0x0/0x24 [<(ptrval)>] arch_local_save_flags+0x0/0x8 [<(ptrval)>] kmem_cache_alloc+0x72/0xac [<(ptrval)>] arch_local_irq_restore+0x0/0x24 [<(ptrval)>] mm_init.isra.7+0xb4/0x104 [<(ptrval)>] __do_execve_file+0x1f8/0x5b4 [<(ptrval)>] do_execve+0x16/0x24 [<(ptrval)>] arch_local_irq_restore+0x0/0x24 [<(ptrval)>] call_usermodehelper_exec_async+0xe0/0x124 [<(ptrval)>] ret_from_kernel_thread+0xc/0x14 [<(ptrval)>] schedule_tail+0x0/0x54 [<(ptrval)>] call_usermodehelper_exec_async+0x0/0x124 ---[ end trace 10ff75dd606d4222 ]--- This is not a a new trace; I had missed it because the "cut here" line is missing from the log. qemu command line: qemu-system-sh4 -M r2d -kernel ./arch/sh/boot/zImage \ -initrd rootfs.cpio \ -append 'rdinit=/sbin/init console=ttySC1,115200 noiotrap' \ -serial null -serial stdio -net nic,model=rtl8139 \ -net user -nographic -monitor null Guenter