On Fri, Mar 01, 2013 at 02:43:53PM +0800, Simon Jeons wrote: > Date: Fri, 01 Mar 2013 14:43:53 +0800 > From: Simon Jeons <simon.jeons@xxxxxxxxx> > To: Mel Gorman <mgorman@xxxxxxx> > CC: Ingo Molnar <mingo@xxxxxxxxxx>, Andrew Morton > <akpm@xxxxxxxxxxxxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, > linux-mm@xxxxxxxxx, riel@xxxxxxxxxx, mhocko@xxxxxxx, hannes@xxxxxxxxxxx > Subject: Re: [PATCH] x86: mm: Check if PUD is large when validating a > kernel address v2 > User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130221 > Thunderbird/17.0.3 > > On 02/13/2013 07:02 PM, Mel Gorman wrote: > >Andrew or Ingo, please pick up. > > > >Changelog since v1 > > o Add reviewed-bys and acked-bys > > > >A user reported a bug whereby a backup process accessing /proc/kcore > >caused an oops. > > > > BUG: unable to handle kernel paging request at ffffbb00ff33b000 > > IP: [<ffffffff8103157e>] kern_addr_valid+0xbe/0x110 > > PGD 0 > > Oops: 0000 [#1] SMP > > CPU 6 > > Modules linked in: af_packet nfs lockd fscache auth_rpcgss nfs_acl sunrpc 8021q garp stp llc cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq mperf microcode fuse nls_iso8859_1 nls_cp437 vfat fat loop dm_mod ioatdma ipv6 ipv6_lib igb dca i7core_edac edac_core i2c_i801 i2c_core cdc_ether usbnet bnx2 mii iTCO_wdt iTCO_vendor_support shpchp rtc_cmos pci_hotplug tpm_tis sg tpm pcspkr tpm_bios serio_raw button ext3 jbd mbcache uhci_hcd ehci_hcd usbcore sd_mod crc_t10dif usb_common processor thermal_sys hwmon scsi_dh_emc scsi_dh_rdac scsi_dh_alua scsi_dh_hp_sw scsi_dh ata_generic ata_piix libata megaraid_sas scsi_mod > > > > Pid: 16196, comm: Hibackp Not tainted 3.0.13-0.27-default #1 IBM System x3550 M3 -[7944 K3G]-/94Y7614 > > RIP: 0010:[<ffffffff8103157e>] [<ffffffff8103157e>] kern_addr_valid+0xbe/0x110 > > RSP: 0018:ffff88094165fe80 EFLAGS: 00010246 > > RAX: 00003300ff33b000 RBX: ffff880100000000 RCX: 0000000000000000 > > RDX: 0000000100000000 RSI: ffff880000000000 RDI: ff32b300ff33b400 > > RBP: 0000000000001000 R08: 00003ffffffff000 R09: 0000000000000000 > > R10: 22302e31223d6e6f R11: 0000000000000246 R12: 0000000000001000 > > R13: 0000000000003000 R14: 0000000000571be0 R15: ffff88094165ff50 > > FS: 00007ff152d33700(0000) GS:ffff88097f2c0000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b > > CR2: ffffbb00ff33b000 CR3: 00000009405a3000 CR4: 00000000000006e0 > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > > Process Hibackp (pid: 16196, threadinfo ffff88094165e000, task ffff8808eb9ba600) > > Stack: > > ffffffff811b8aaa 0000000000004000 ffff880943fea480 ffff8808ef2bae50 > > ffff880943d32980 fffffffffffffffb ffff8808ef2bae40 ffff88094165ff50 > > 0000000000004000 000000000056ebe0 ffffffff811ad847 000000000056ebe0 > > Call Trace: > > [<ffffffff811b8aaa>] read_kcore+0x17a/0x370 > > [<ffffffff811ad847>] proc_reg_read+0x77/0xc0 > > [<ffffffff81151687>] vfs_read+0xc7/0x130 > > [<ffffffff811517f3>] sys_read+0x53/0xa0 > > [<ffffffff81449692>] system_call_fastpath+0x16/0x1b > > > >Investigation determined that the bug triggered when reading system RAM > >at the 4G mark. On this system, that was the first address using 1G pages > > Do you mean there is one page which is 1G? > 1GB support in native kernel is started from 2.6.27 with these 2 commits: 39c11e6 and b4718e6. For Intel CPU, from Westmere it supports 1GB page. BTW, IBM System x3550 M3 is a Westmere based system.
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