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    Subject[ 13/36] drivers/base/memory.c: fix show_mem_removable() to handle missing sections
    Date
    3.10-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Russ Anderson <rja@sgi.com>

    commit 21ea9f5ace3a7317cc3ba1fbc749758021a83136 upstream.

    "cat /sys/devices/system/memory/memory*/removable" crashed the system.

    The problem is that show_mem_removable() is passing a
    bad pfn to is_mem_section_removable(), which causes

    if (!node_online(page_to_nid(page)))

    to blow up. Why is it passing in a bad pfn?

    The reason is that show_mem_removable() will loop sections_per_block
    times. sections_per_block is 16, but mem->section_count is 8,
    indicating holes in this memory block. Checking that the memory section
    is present before checking to see if the memory section is removable
    fixes the problem.

    harp5-sys:~ # cat /sys/devices/system/memory/memory*/removable
    0
    1
    1
    1
    1
    1
    1
    1
    1
    1
    1
    1
    1
    1
    BUG: unable to handle kernel paging request at ffffea00c3200000
    IP: [<ffffffff81117ed1>] is_pageblock_removable_nolock+0x1/0x90
    PGD 83ffd4067 PUD 37bdfce067 PMD 0
    Oops: 0000 [#1] SMP
    Modules linked in: autofs4 binfmt_misc rdma_ucm rdma_cm iw_cm ib_addr ib_srp scsi_transport_srp scsi_tgt ib_ipoib ib_cm ib_uverbs ib_umad iw_cxgb3 cxgb3 mdio mlx4_en mlx4_ib ib_sa mlx4_core ib_mthca ib_mad ib_core fuse nls_iso8859_1 nls_cp437 vfat fat joydev loop hid_generic usbhid hid hwperf(O) numatools(O) dm_mod iTCO_wdt ipv6 iTCO_vendor_support igb i2c_i801 ioatdma i2c_algo_bit ehci_pci pcspkr lpc_ich i2c_core ehci_hcd ptp sg mfd_core dca rtc_cmos pps_core mperf button xhci_hcd sd_mod crc_t10dif usbcore usb_common scsi_dh_emc scsi_dh_hp_sw scsi_dh_alua scsi_dh_rdac scsi_dh gru(O) xvma(O) xfs crc32c libcrc32c thermal sata_nv processor piix mptsas mptscsih scsi_transport_sas mptbase megaraid_sas fan thermal_sys hwmon ext3 jbd ata_piix ahci libahci libata scsi_mod
    CPU: 4 PID: 5991 Comm: cat Tainted: G O 3.11.0-rc5-rja-uv+ #10
    Hardware name: SGI UV2000/ROMLEY, BIOS SGI UV 2000/3000 series BIOS 01/15/2013
    task: ffff88081f034580 ti: ffff880820022000 task.ti: ffff880820022000
    RIP: 0010:[<ffffffff81117ed1>] [<ffffffff81117ed1>] is_pageblock_removable_nolock+0x1/0x90
    RSP: 0018:ffff880820023df8 EFLAGS: 00010287
    RAX: 0000000000040000 RBX: ffffea00c3200000 RCX: 0000000000000004
    RDX: ffffea00c30b0000 RSI: 00000000001c0000 RDI: ffffea00c3200000
    RBP: ffff880820023e38 R08: 0000000000000000 R09: 0000000000000001
    R10: 0000000000000000 R11: 0000000000000001 R12: ffffea00c33c0000
    R13: 0000160000000000 R14: 6db6db6db6db6db7 R15: 0000000000000001
    FS: 00007ffff7fb2700(0000) GS:ffff88083fc80000(0000) knlGS:0000000000000000
    CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: ffffea00c3200000 CR3: 000000081b954000 CR4: 00000000000407e0
    Call Trace:
    show_mem_removable+0x41/0x70
    dev_attr_show+0x2a/0x60
    sysfs_read_file+0xf7/0x1c0
    vfs_read+0xc8/0x130
    SyS_read+0x5d/0xa0
    system_call_fastpath+0x16/0x1b

    Signed-off-by: Russ Anderson <rja@sgi.com>
    Cc: "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
    Cc: Yinghai Lu <yinghai@kernel.org>
    Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    drivers/base/memory.c | 2 ++
    1 file changed, 2 insertions(+)

    --- a/drivers/base/memory.c
    +++ b/drivers/base/memory.c
    @@ -152,6 +152,8 @@ static ssize_t show_mem_removable(struct
    container_of(dev, struct memory_block, dev);

    for (i = 0; i < sections_per_block; i++) {
    + if (!present_section_nr(mem->start_section_nr + i))
    + continue;
    pfn = section_nr_to_pfn(mem->start_section_nr + i);
    ret &= is_mem_section_removable(pfn, PAGES_PER_SECTION);
    }



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