From 22880ebe76be421a572b6f004604467c63f281f5 Mon Sep 17 00:00:00 2001 From: Yasuaki Ishimatsu Date: Thu, 9 Oct 2014 15:29:07 -0700 Subject: [PATCH] drivers/firmware/memmap.c: don't create memmap sysfs of same firmware_map_entry 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 Cc: Santosh Shilimkar Cc: Toshi Kani Cc: Greg Kroah-Hartman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/firmware/memmap.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/drivers/firmware/memmap.c b/drivers/firmware/memmap.c index 79f18e6d9c4f..cc016c615c19 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) -- 2.30.2