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linux/drivers/firmware
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Yasuaki Ishimatsu 22880ebe76 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 <isimatu.yasuaki@jp.fujitsu.com>
Cc: Santosh Shilimkar <santosh.shilimkar@ti.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-10-09 22:26:00 -04:00
..
efi Revert "efi/x86: efistub: Move shared dependencies to <asm/efi.h>" 2014-09-23 22:01:55 +01:00
google firmware: google memconsole driver fixes 2014-02-15 11:30:28 -08:00
dcdbas.c initconst: Fix initconst mistake in dcdbas 2014-02-13 18:14:54 -08:00
dcdbas.h
dell_rbu.c
dmi_scan.c firmware/dmi_scan: generalize for use by other archs 2014-01-23 16:36:57 -08:00
dmi-id.c dmi-id: fix a memory leak in dmi_id_init error path 2010-08-05 13:53:34 -07:00
dmi-sysfs.c firmware: dmi-sysfs: Remove "dmi" directory on module exit 2013-12-08 18:23:42 -08:00
edd.c [SCSI] edd: Treat "XPRS" host bus type the same as "PCI" 2011-10-31 13:26:19 +04:00
iscsi_ibft_find.c efi: Make 'efi_enabled' a function to query EFI facilities 2013-01-30 11:51:59 -08:00
iscsi_ibft.c iscsi_ibft: Fix finding Broadcom specific ibft sign 2014-05-13 14:54:14 -04:00
Kconfig ACPI and power management updates for 3.14-rc1 2014-01-24 15:51:02 -08:00
Makefile x86/efi: Don't select EFI from certain special ACPI drivers 2013-12-19 21:32:46 +01:00
memmap.c drivers/firmware/memmap.c: don't create memmap sysfs of same firmware_map_entry 2014-10-09 22:26:00 -04:00
pcdp.c pcdp: use early_ioremap/early_iounmap to access pcdp table 2012-07-30 17:25:11 -07:00
pcdp.h Update broken web addresses in the kernel. 2010-10-18 11:03:14 +02:00