From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-x235.google.com (mail-wi0-x235.google.com [IPv6:2a00:1450:400c:c05::235]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority" (not verified)) by ozlabs.org (Postfix) with ESMTPS id E94BF2C00EC for ; Mon, 12 Aug 2013 21:08:35 +1000 (EST) Received: by mail-wi0-f181.google.com with SMTP id en1so1538955wid.14 for ; Mon, 12 Aug 2013 04:08:26 -0700 (PDT) Message-ID: <5208C1CD.3040601@gmail.com> Date: Mon, 12 Aug 2013 13:06:53 +0200 From: Wladislav Wiebe MIME-Version: 1.0 To: Aaro Koskinen Subject: Re: mm/slab: ppc: ubi: kmalloc_slab WARNING / PPC + UBI driver References: <51F8F827.6020108@gmail.com> <20130731173434.GA27470@blackmetal.musicnaut.iki.fi> In-Reply-To: <20130731173434.GA27470@blackmetal.musicnaut.iki.fi> Content-Type: text/plain; charset=ISO-8859-1 Cc: dedekind1@gmail.com, dwmw2@infradead.org, penberg@kernel.org, linux-mm@kvack.org, linux-mtd@lists.infradead.org, cl@linux.com, linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi guys, we got the real root cause of the allocation issue: Subject: [PATCH 1/1] of: fdt: fix memory initialization for expanded DT Already existing property flags are filled wrong for properties created from initial FDT. This could cause problems if this DYNAMIC device-tree functions are used later, i.e. properties are attached/detached/replaced. Simply dumping flags from the running system show, that some initial static (not allocated via kzmalloc()) nodes are marked as dynamic. I putted some debug extensions to property_proc_show(..) : .. + if (OF_IS_DYNAMIC(pp)) + pr_err("DEBUG: xxx : OF_IS_DYNAMIC\n"); + if (OF_IS_DETACHED(pp)) + pr_err("DEBUG: xxx : OF_IS_DETACHED\n"); when you operate on the nodes (e.g.: ~$ cat /proc/device-tree/*some_node*) you will see that those flags are filled wrong, basically in most cases it will dump a DYNAMIC or DETACHED status, which is in not true. (BTW. this OF_IS_DETACHED is a own define for debug purposes which which just make a test_bit(OF_DETACHED, &x->_flags) If nodes are dynamic kernel is allowed to kfree() them. But it will crash attempting to do so on the nodes from FDT -- they are not allocated via kzmalloc(). Signed-off-by: Wladislav Wiebe --- drivers/of/fdt.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c index 6bb7cf2..b10ba00 100644 --- a/drivers/of/fdt.c +++ b/drivers/of/fdt.c @@ -392,6 +392,8 @@ static void __unflatten_device_tree(struct boot_param_header *blob, mem = (unsigned long) dt_alloc(size + 4, __alignof__(struct device_node)); + memset((void *)mem, 0, size); + ((__be32 *)mem)[size / 4] = cpu_to_be32(0xdeadbeef); pr_debug(" unflattening %lx...\n", mem); -- 1.7.1 This is committed to the mainline - hope it comes in soon. Thanks & BR, Wladislav Wiebe On 31/07/13 19:34, Aaro Koskinen wrote: > Hi, > > On Wed, Jul 31, 2013 at 01:42:31PM +0200, Wladislav Wiebe wrote: >> DEBUG: xxx kmalloc_slab, requested 'size' = 8388608, KMALLOC_MAX_SIZE = 4194304 > [...] >> [ccd3be60] [c0099fd4] kmalloc_slab+0x48/0xe8 (unreliable) >> [ccd3be70] [c00ae650] __kmalloc+0x20/0x1b4 >> [ccd3be90] [c00d46f4] seq_read+0x2a4/0x540 >> [ccd3bee0] [c00fe09c] proc_reg_read+0x5c/0x90 >> [ccd3bef0] [c00b4e1c] vfs_read+0xa4/0x150 >> [ccd3bf10] [c00b500c] SyS_read+0x4c/0x84 >> [ccd3bf40] [c000be80] ret_from_syscall+0x0/0x3c > > It seems some procfs file is trying to dump 8 MB at a single go. You > need to fix that to return data in smaller chunks. What file is it? > > A. >