The patch titled Subject: drivers/firmware/memmap.c: don't allocate firmware_map_entry of same memory range has been removed from the -mm tree. Its filename was dont-allocate-firmware_map_entry-of-same-memory-range.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx> Subject: drivers/firmware/memmap.c: don't allocate firmware_map_entry of same memory range When limiting memory by mem= and ACPI DSDT table has PNP0C80, firmware_map_entrys of same memory range are allocated and memmap X sysfses which have same memory range are created as follows: # cat /sys/firmware/memmap/0/* 0x407ffffffff 0x40000000000 System RAM # cat /sys/firmware/memmap/33/* 0x407ffffffff 0x40000000000 System RAM # cat /sys/firmware/memmap/35/* 0x407ffffffff 0x40000000000 System RAM In this case, when hot-removing memory, kernel panic occurs, showing following call trace: BUG: unable to handle kernel paging request at 00000001003e000b IP: [<ffffffff81225c26>] sysfs_open_file+0x46/0x2b0 PGD 203a89fe067 PUD 0 Oops: 0000 [#1] SMP ... Call Trace: [<ffffffff811ad95f>] do_dentry_open+0x1ef/0x2a0 [<ffffffff811bba32>] ? __inode_permission+0x52/0xc0 [<ffffffff81225be0>] ? sysfs_schedule_callback+0x1c0/0x1c0 [<ffffffff811ada41>] finish_open+0x31/0x40 [<ffffffff811bf6ac>] do_last+0x57c/0x1220 [<ffffffff8119529e>] ? kmem_cache_alloc_trace+0x1ce/0x1f0 [<ffffffff811c0412>] path_openat+0xc2/0x4c0 [<ffffffff81167e2c>] ? tlb_flush_mmu.part.53+0x4c/0x90 [<ffffffff811c102b>] do_filp_open+0x4b/0xb0 [<ffffffff811cd827>] ? __alloc_fd+0xa7/0x130 [<ffffffff811aeed3>] do_sys_open+0xf3/0x1f0 [<ffffffff811aefee>] SyS_open+0x1e/0x20 [<ffffffff815f2199>] system_call_fastpath+0x16/0x1b The problem occurs as follows: When calling e820_reserve_resources(), firmware_map_entrys of all e820 memory map are allocated. And all firmware_map_entrys is added map_entries list as follows: map_entries -> +--- entry A --------+ -> ... | start 0x407ffffffff| | end 0x40000000000| | type System RAM | +--------------------+ After that, if ACPI DSDT table has PNP0C80 and the memory range is limited by mem=, the PNP0C80 is hot-added. Then firmware_map_entry of PNP0C80 is allocated and added map_entries list as follows: map_entries -> +--- entry A --------+ -> ... -> +--- entry B --------+ | start 0x407ffffffff| | start 0x407ffffffff| | end 0x40000000000| | end 0x40000000000| | type System RAM | | type System RAM | +--------------------+ +--------------------+ Then memmap 0 sysfs for entry B is created. After that, firmware_memmap_init() creates memmap sysfses of all firmware_map_entrys in map_entries list. As a result, memmap 33 sysfs for entry A and memmap 35 sysfs for entry B are created. But kobject of entry B has been used by memmap 0 sysfs. So when creating memmap 35 sysfs, the kobject is broken. If hot-removing memory, memmap 0 sysfs is destroyed and kobject of memmap 0 sysfs is freed. But the kobject can be accessed via memmap 35 sysfs. So when open memmap 35 sysfs, kernel panic occurs. This patch checks whether there is firmware_map_entry of same memory range in map_entries list and don't allocate firmware_map_entry of same memroy range. Signed-off-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx> Cc: Santosh Shilimkar <santosh.shilimkar@xxxxxx> Cc: Toshi Kani <toshi.kani@xxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/firmware/memmap.c | 4 ++++ 1 file changed, 4 insertions(+) diff -puN drivers/firmware/memmap.c~dont-allocate-firmware_map_entry-of-same-memory-range drivers/firmware/memmap.c --- a/drivers/firmware/memmap.c~dont-allocate-firmware_map_entry-of-same-memory-range +++ a/drivers/firmware/memmap.c @@ -286,6 +286,10 @@ int __meminit firmware_map_add_hotplug(u { struct firmware_map_entry *entry; + entry = firmware_map_find_entry(start, end - 1, type); + if (entry) + return 0; + entry = firmware_map_find_entry_bootmem(start, end - 1, type); if (!entry) { entry = kzalloc(sizeof(struct firmware_map_entry), GFP_ATOMIC); _ Patches currently in -mm which might be from isimatu.yasuaki@xxxxxxxxxxxxxx are origin.patch x86mem-hotplug-pass-sync_global_pgds-a-correct-argument-in-remove_pagetable.patch x86mem-hotplug-modify-pgd-entry-when-removing-memory.patch x86-numa-setup_node_data-drop-dead-code-and-rename-function.patch x86-numa-setup_node_data-drop-dead-code-and-rename-function-v2.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html