From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f174.google.com (mail-pd0-f174.google.com [209.85.192.174]) by kanga.kvack.org (Postfix) with ESMTP id E17AE6B0039 for ; Tue, 30 Sep 2014 05:26:44 -0400 (EDT) Received: by mail-pd0-f174.google.com with SMTP id y13so2488103pdi.19 for ; Tue, 30 Sep 2014 02:26:44 -0700 (PDT) Received: from fgwmail6.fujitsu.co.jp (fgwmail6.fujitsu.co.jp. [192.51.44.36]) by mx.google.com with ESMTPS id c7si26445513pat.121.2014.09.30.02.26.43 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Tue, 30 Sep 2014 02:26:44 -0700 (PDT) Received: from kw-mxq.gw.nic.fujitsu.com (unknown [10.0.237.131]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id 776FB3EE0AE for ; Tue, 30 Sep 2014 18:26:42 +0900 (JST) Received: from s4.gw.fujitsu.co.jp (s4.gw.fujitsu.co.jp [10.0.50.94]) by kw-mxq.gw.nic.fujitsu.com (Postfix) with ESMTP id 7C88FAC067C for ; Tue, 30 Sep 2014 18:26:41 +0900 (JST) Received: from g01jpfmpwkw03.exch.g01.fujitsu.local (g01jpfmpwkw03.exch.g01.fujitsu.local [10.0.193.57]) by s4.gw.fujitsu.co.jp (Postfix) with ESMTP id 25AB8E38001 for ; Tue, 30 Sep 2014 18:26:41 +0900 (JST) Message-ID: <542A771C.9040605@jp.fujitsu.com> Date: Tue, 30 Sep 2014 18:25:48 +0900 From: Yasuaki Ishimatsu MIME-Version: 1.0 Subject: [PATCH] driver/firmware/memmap: don't create memmap sysfs of same firmware_map_entry Content-Type: text/plain; charset="ISO-2022-JP" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org By the following commits, we prevented from allocating firmware_map_entry of same memory range: f0093ede: drivers/firmware/memmap.c: don't allocate firmware_map_entry of same memory range 49c8b24d: drivers/firmware/memmap.c: pass the correct argument to firmware_map_find_entry_bootmem() But it's not enough. When PNP0C80 device is added by acpi_scan_init(), memmap sysfses of same firmware_map_entry are created twice as follows: # cat /sys/firmware/memmap/*/start 0x40000000000 0x60000000000 0x4a837000 0x4a83a000 0x4a8b5000 ... 0x40000000000 0x60000000000 ... The flows of the issues are as follows: 1. e820_reserve_resources() allocates firmware_map_entrys of all memory ranges defined in e820. And, these firmware_map_entrys are linked with map_entries list. map_entries -> entry 1 -> ... -> entry N 2. When PNP0C80 device is limited by mem= boot option, acpi_scan_init() added the memory device. In this case, firmware_map_add_hotplug() allocates firmware_map_entry and creates memmap sysfs. map_entries -> entry 1 -> ... -> entry N -> entry N+1 | memmap 1 3. firmware_memmap_init() creates memmap sysfses of firmware_map_entrys linked with map_entries. map_entries -> entry 1 -> ... -> entry N -> entry N+1 | | | memmap 2 memmap N+1 memmap 1 memmap N+2 So while hot removing the PNP0C80 device, kernel panic occurs as follows: BUG: unable to handle kernel paging request at 00000001003e000b IP: sysfs_open_file+0x46/0x2b0 PGD 203a89fe067 PUD 0 Oops: 0000 [#1] SMP ... Call Trace: do_dentry_open+0x1ef/0x2a0 finish_open+0x31/0x40 do_last+0x57c/0x1220 path_openat+0xc2/0x4c0 do_filp_open+0x4b/0xb0 do_sys_open+0xf3/0x1f0 SyS_open+0x1e/0x20 system_call_fastpath+0x16/0x1b The patch adds a check of confirming whether memmap sysfs of firmware_map_entry has been created, and does not create memmap sysfs of same firmware_map_entry. Signed-off-by: Yasuaki Ishimatsu --- drivers/firmware/memmap.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/firmware/memmap.c b/drivers/firmware/memmap.c index 79f18e6..cc016c6 100644 --- a/drivers/firmware/memmap.c +++ b/drivers/firmware/memmap.c @@ -184,6 +184,9 @@ static int add_sysfs_fw_map_entry(struct firmware_map_entry *entry) static int map_entries_nr; static struct kset *mmap_kset; + if (entry->kobj.state_in_sysfs) + return -EEXIST; + if (!mmap_kset) { mmap_kset = kset_create_and_add("memmap", NULL, firmware_kobj); if (!mmap_kset) -- 1.8.3.1 -- 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