Re: [PATCH v2] [BUGFIX] drivers/base: fix show_mem_removable to handlemissing sections

[Yasuaki Ishimatsu]

(2013/08/24 1:23), Russ Anderson wrote:
> "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?
>
> 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.
>
> v2: Add change suggested by Yasuaki Ishimatsu.
>
> Signed-off-by: Russ Anderson <rja@xxxxxxx>

Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>

Thanks,
Yasuaki Ishimatsu


> The failing output:
> -----------------------------------------------------------
> harp5-sys:~ # cat /sys/devices/system/memory/memory*/removable
> 0
> 1
> 1
> 1
> 1
> 1
> 1
> 1
> 1
> 1
> 1
> 1
> 1
> 1
> [  372.111178] BUG: unable to handle kernel paging request at ffffea00c3200000
> [  372.119230] IP: [<ffffffff81117ed1>] is_pageblock_removable_nolock+0x1/0x90
> [  372.127022] PGD 83ffd4067 PUD 37bdfce067 PMD 0
> [  372.132109] Oops: 0000 [#1] SMP
> [  372.135730] 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
> [  372.213536] CPU: 4 PID: 5991 Comm: cat Tainted: G           O 3.11.0-rc5-rja-uv+ #10
> [  372.222173] Hardware name: SGI UV2000/ROMLEY, BIOS SGI UV 2000/3000 series BIOS 01/15/2013
> [  372.231391] task: ffff88081f034580 ti: ffff880820022000 task.ti: ffff880820022000
> [  372.239737] RIP: 0010:[<ffffffff81117ed1>]  [<ffffffff81117ed1>] is_pageblock_removable_nolock+0x1/0x90
> [  372.250229] RSP: 0018:ffff880820023df8  EFLAGS: 00010287
> [  372.256151] RAX: 0000000000040000 RBX: ffffea00c3200000 RCX: 0000000000000004
> [  372.264111] RDX: ffffea00c30b0000 RSI: 00000000001c0000 RDI: ffffea00c3200000
> [  372.272071] RBP: ffff880820023e38 R08: 0000000000000000 R09: 0000000000000001
> [  372.280030] R10: 0000000000000000 R11: 0000000000000001 R12: ffffea00c33c0000
> [  372.287987] R13: 0000160000000000 R14: 6db6db6db6db6db7 R15: 0000000000000001
> [  372.295945] FS:  00007ffff7fb2700(0000) GS:ffff88083fc80000(0000) knlGS:0000000000000000
> [  372.304970] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  372.311378] CR2: ffffea00c3200000 CR3: 000000081b954000 CR4: 00000000000407e0
> [  372.319335] Stack:
> [  372.321575]  ffff880820023e38 ffffffff81161e94 ffffffff81d9e940 0000000000000009
> [  372.329872]  0000000000000000 ffff8817bb97b800 ffff88081e928000 ffff8817bb97b870
> [  372.338167]  ffff880820023e68 ffffffff813730d1 fffffffffffffffb ffffffff81a97600
> [  372.346463] Call Trace:
> [  372.349201]  [<ffffffff81161e94>] ? is_mem_section_removable+0x84/0x110
> [  372.356579]  [<ffffffff813730d1>] show_mem_removable+0x41/0x70
> [  372.363094]  [<ffffffff8135be8a>] dev_attr_show+0x2a/0x60
> [  372.369122]  [<ffffffff811e1817>] sysfs_read_file+0xf7/0x1c0
> [  372.375441]  [<ffffffff8116e7e8>] vfs_read+0xc8/0x130
> [  372.381076]  [<ffffffff8116ee5d>] SyS_read+0x5d/0xa0
> [  372.386624]  [<ffffffff814bfa12>] system_call_fastpath+0x16/0x1b
> [  372.393313] Code: 01 00 00 00 e9 3c ff ff ff 90 0f b6 4a 30 44 89 d8 d3 e0 89 c1 83 e9 01 48 63 c9 49 01 c8 eb 92 66 2e 0f 1f 84 00 00 00 00 00 55 <48> 8b 0f 49 89 f8 48 89 e5 48 89 ca 48 c1 ea 36 0f a3 15 d8 2f
> [  372.415032] RIP  [<ffffffff81117ed1>] is_pageblock_removable_nolock+0x1/0x90
> [  372.422905]  RSP <ffff880820023df8>
> [  372.426792] CR2: ffffea00c3200000
> ---------------------------------------------------------
>
>
> ---
>   drivers/base/memory.c |    2 ++
>   1 file changed, 2 insertions(+)
>
> Index: linux/drivers/base/memory.c
> ===================================================================
> --- linux.orig/drivers/base/memory.c	2013-08-23 11:09:32.433772674 -0500
> +++ linux/drivers/base/memory.c	2013-08-23 11:21:13.338046321 -0500
> @@ -141,6 +141,8 @@ 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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