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New: BUG: unable to handle kernel NULL pointer dereference at (null)

Bug 26242 Andrew Morton 2 participants 4 messages Jan 6, 2011 – Jan 18, 2011 1 message not in the archive Btrfs file system

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Andrew Morton

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(switched to email. Please respond via emailed reply-to-all, not via the bugzilla web interface).

Quoted 107 lines · On Thu, 6 Jan 2011 20:59:08 GMT [email protected] wrote:

https://bugzilla.kernel.org/show_bug.cgi?id=26242

Summary: BUG: unable to handle kernel NULL pointer dereference
at (null)
Product: Memory Management
Version: 2.5
Kernel Version: 2.6.37
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: low
Priority: P1
Component: Other
AssignedTo: [email protected]
ReportedBy: [email protected]
Regression: No

My system crashed with the following output:

___

Jan  6 20:06:22 eser kernel: [19365.562621] BUG: unable to handle kernel NULL
pointer dereference at   (null)
Jan  6 20:06:22 eser kernel: [19365.562675] IP: [<c022989b>]
kmap_atomic_prot+0x1b/0x100
Jan  6 20:06:22 eser kernel: [19365.562709] *pde = 00000000 
Jan  6 20:06:22 eser kernel: [19365.562726] Oops: 0000 [#1] PREEMPT SMP 
Jan  6 20:06:22 eser kernel: [19365.562752] last sysfs file:
/sys/devices/platform/coretemp.0/temp1_input
Jan  6 20:06:22 eser kernel: [19365.562777] Modules linked in: isofs usblp

usb_storage uas nls_utf8 udf crc_itu_t fuse ipt_MASQUERADE xt_pkttype xt_TCPMSS xt_tcpudp ipt_LOG xt_limit iptable_nat nf_nat snd_pcm_oss snd_mixer_oss snd_seq snd_seq_device xt_NOTRACK ipt_REJECT xt_state iptable_raw iptable_filter nf_conntrack_netbios_ns nf_conntrack_ipv4 nf_conntrack nf_defrag_ipv4 ip_tables cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq mperf speedstep_lib ip6_tables x_tables loop arc4 ecb b43 snd_hda_codec_si3054 mac80211 snd_hda_codec_realtek snd_hda_intel r8169 snd_hda_codec cfg80211 sdhci_pci mii snd_hwdep acer_wmi sdhci snd_pcm rfkill iTCO_wdt yenta_socket ssb tifm_7xx1 iTCO_vendor_support sg sr_mod mmc_core snd_timer pcmcia_core tifm_core cdrom pcspkr wmi pcmcia_rsrc psmouse snd i2c_i801 shpchp evdev soundcore battery rng_core ac snd_page_alloc pci_hotplug dm_crypt usbhid hid nouveau ttm drm_kms_helper drm uhci_hcd rtc_cmos ata_piix i2c_algo_bit i2c_core rtc_core cfbcopyarea ehci_hcd usb

Jan  6 20:06:22 eser kernel: core video cfbimgblt cfbfillrect rtc_lib output

button nls_base dm_snapshot sha512_generic sha256_generic xts cbc aes_i586 aes_generic cfq_iosched blk_cgroup btrfs zlib_deflate libcrc32c reiserfs ahci libahci libata coretemp hwmon fan thermal processor unix [last unloaded:
pktcdvd]

Jan  6 20:06:22 eser kernel: [19365.563014] 
Jan  6 20:06:22 eser kernel: [19365.563014] Pid: 15675, comm: gimp-2.6 Not
tainted 2.6.37 #1 Myall2                         /Aspire 9410
Jan  6 20:06:22 eser kernel: [19365.563014] EIP: 0060:[<c022989b>] EFLAGS:
00010202 CPU: 0
Jan  6 20:06:22 eser kernel: [19365.563014] EIP is at
kmap_atomic_prot+0x1b/0x100
Jan  6 20:06:22 eser kernel: [19365.563014] EAX: 00000000 EBX: 00000600 ECX:
f3a82000 EDX: 00000163
Jan  6 20:06:23 eser kernel: [19365.563014] ESI: f3a83eac EDI: 00000000 EBP:
f3a83db8 ESP: f3a83da8
Jan  6 20:06:23 eser kernel: [19365.563014]  DS: 007b ES: 007b FS: 00d8 GS:
0033 SS: 0068
Jan  6 20:06:23 eser kernel: [19365.563014] Process gimp-2.6 (pid: 15675,
ti=f3a82000 task=eaf28000 task.ti=f3a82000)
Jan  6 20:06:23 eser kernel: [19365.563014] Stack:
Jan  6 20:06:23 eser kernel: [19365.563014]  f3a83dc0 00000600 f3a83eac
00000000 f3a83dc0 c022998e f3a83dd8 c0299c0c
Jan  6 20:06:23 eser kernel: [19365.563014]  e0359240 00000600 00001000
00001000 f3a83dfc f828d6da 00000600 00001008
Jan  6 20:06:23 eser kernel: [19365.563014]  00000002 00000000 00000002
00002000 00001608 f3a83ed0 f828e1ff 00001608
Jan  6 20:06:23 eser kernel: [19365.563014] Call Trace:
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c022998e>] ?
__kmap_atomic+0xe/0x10
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c0299c0c>] ?
iov_iter_copy_from_user_atomic+0x3c/0x90
Jan  6 20:06:23 eser kernel: [19365.563014]  [<f828d6da>] ?
btrfs_copy_from_user+0x5a/0xb0 [btrfs]
Jan  6 20:06:23 eser kernel: [19365.563014]  [<f828e1ff>] ?
btrfs_file_aio_write+0x52f/0x9c0 [btrfs]
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d0810>] ?
__mem_cgroup_commit_charge+0x70/0xe0
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d672c>] ?
do_sync_write+0x9c/0xd0
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d6b15>] ?
rw_verify_area+0x65/0x100
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d6e7a>] ?
vfs_write+0x9a/0x160
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d8211>] ?
fget_light+0x91/0xb0
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d6690>] ?
do_sync_write+0x0/0xd0
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d714d>] ? sys_write+0x3d/0x70
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c0202e18>] ?
sysenter_do_call+0x12/0x28
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c04e0000>] ?
quirk_amd_ide_mode+0x40/0x95
Jan  6 20:06:23 eser kernel: [19365.563014] Code: 8b 15 4c 6a 6b c0 55 89 e5 e8
e2 f8 ff ff 5d c3 55 89 e5 83 ec 10 89 e1 81 e1 00 e0 ff ff 89 5d f4 89 75 f8
89 7d fc 83 41 14 01 <8b> 08 c1 e9 1e 69 d9 40 03 00 00 8d 8b c0 42 64 c0 2b 8b
cc 45 
Jan  6 20:06:23 eser kernel: [19365.563014] EIP: [<c022989b>]
kmap_atomic_prot+0x1b/0x100 SS:ESP 0068:f3a83da8
Jan  6 20:06:23 eser kernel: [19365.563014] CR2: 0000000000000000
Jan  6 20:06:23 eser kernel: [19365.568714] ---[ end trace afc2be06c7d06a71
]---
Jan  6 20:06:23 eser kernel: [19365.568724] note: gimp-2.6[15675] exited with
Quoted 4 lines

preempt_count 2
___

The kernel is an unpatched v2.6.37. I have not seen something like this before.

Bugzilla's habit of wordwrapping oops traces is fantastically irritating. Please use attachments to avoid this.

Either Peter's new kmap_atomic() stuff blew up or BTRFS is playing around with a NULL page*. I'd wager on the latter.

Thanks, I'll ask Rafael and Maciej to track this as a 2.6.36->2.6.37 regression.

#2 lore raw

A similar bug has been reported by Kenneth Lakin [[email protected]] last week. It's related to my check-in (git commit 914ee295af418e936ec20a08c1663eaabe4cd07a). I am looking into it now.

I found one suspicious code in prepage_pages (fs/btrfs/file.c):

        start_pos = pos & ~((u64)root->sectorsize - 1);
        last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;

root->sectorsize is used at first, but PAGE_SIZE is used after it. Do we assume these two values are always the same?

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Andrew Morton
Sent: Friday, January 07, 2011 5:13 AM
To: [email protected]
Cc: [email protected]; Peter Zijlstra; [email protected]; [email protected]
Subject: Re: [Bug 26242] New: BUG: unable to handle kernel NULL pointer dereference at (null)

(switched to email. Please respond via emailed reply-to-all, not via the bugzilla web interface).

Quoted 107 lines · On Thu, 6 Jan 2011 20:59:08 GMT [email protected] wrote:

https://bugzilla.kernel.org/show_bug.cgi?id=26242

Summary: BUG: unable to handle kernel NULL pointer dereference
at (null)
Product: Memory Management
Version: 2.5
Kernel Version: 2.6.37
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: low
Priority: P1
Component: Other
AssignedTo: [email protected]
ReportedBy: [email protected]
Regression: No

My system crashed with the following output:

___

Jan  6 20:06:22 eser kernel: [19365.562621] BUG: unable to handle kernel NULL
pointer dereference at   (null)
Jan  6 20:06:22 eser kernel: [19365.562675] IP: [<c022989b>]
kmap_atomic_prot+0x1b/0x100
Jan  6 20:06:22 eser kernel: [19365.562709] *pde = 00000000 
Jan  6 20:06:22 eser kernel: [19365.562726] Oops: 0000 [#1] PREEMPT SMP 
Jan  6 20:06:22 eser kernel: [19365.562752] last sysfs file:
/sys/devices/platform/coretemp.0/temp1_input
Jan  6 20:06:22 eser kernel: [19365.562777] Modules linked in: isofs usblp

usb_storage uas nls_utf8 udf crc_itu_t fuse ipt_MASQUERADE xt_pkttype xt_TCPMSS xt_tcpudp ipt_LOG xt_limit iptable_nat nf_nat snd_pcm_oss snd_mixer_oss snd_seq snd_seq_device xt_NOTRACK ipt_REJECT xt_state iptable_raw iptable_filter nf_conntrack_netbios_ns nf_conntrack_ipv4 nf_conntrack nf_defrag_ipv4 ip_tables cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq mperf speedstep_lib ip6_tables x_tables loop arc4 ecb b43 snd_hda_codec_si3054 mac80211 snd_hda_codec_realtek snd_hda_intel r8169 snd_hda_codec cfg80211 sdhci_pci mii snd_hwdep acer_wmi sdhci snd_pcm rfkill iTCO_wdt yenta_socket ssb tifm_7xx1 iTCO_vendor_support sg sr_mod mmc_core snd_timer pcmcia_core tifm_core cdrom pcspkr wmi pcmcia_rsrc psmouse snd i2c_i801 shpchp evdev soundcore battery rng_core ac snd_page_alloc pci_hotplug dm_crypt usbhid hid nouveau ttm drm_kms_helper drm uhci_hcd rtc_cmos ata_piix i2c_algo_bit i2c_core rtc_core cfbcopyarea ehci_hcd usb

Jan  6 20:06:22 eser kernel: core video cfbimgblt cfbfillrect rtc_lib output

button nls_base dm_snapshot sha512_generic sha256_generic xts cbc aes_i586 aes_generic cfq_iosched blk_cgroup btrfs zlib_deflate libcrc32c reiserfs ahci libahci libata coretemp hwmon fan thermal processor unix [last unloaded:
pktcdvd]

Jan  6 20:06:22 eser kernel: [19365.563014] 
Jan  6 20:06:22 eser kernel: [19365.563014] Pid: 15675, comm: gimp-2.6 Not
tainted 2.6.37 #1 Myall2                         /Aspire 9410
Jan  6 20:06:22 eser kernel: [19365.563014] EIP: 0060:[<c022989b>] EFLAGS:
00010202 CPU: 0
Jan  6 20:06:22 eser kernel: [19365.563014] EIP is at
kmap_atomic_prot+0x1b/0x100
Jan  6 20:06:22 eser kernel: [19365.563014] EAX: 00000000 EBX: 00000600 ECX:
f3a82000 EDX: 00000163
Jan  6 20:06:23 eser kernel: [19365.563014] ESI: f3a83eac EDI: 00000000 EBP:
f3a83db8 ESP: f3a83da8
Jan  6 20:06:23 eser kernel: [19365.563014]  DS: 007b ES: 007b FS: 00d8 GS:
0033 SS: 0068
Jan  6 20:06:23 eser kernel: [19365.563014] Process gimp-2.6 (pid: 15675,
ti=f3a82000 task=eaf28000 task.ti=f3a82000)
Jan  6 20:06:23 eser kernel: [19365.563014] Stack:
Jan  6 20:06:23 eser kernel: [19365.563014]  f3a83dc0 00000600 f3a83eac
00000000 f3a83dc0 c022998e f3a83dd8 c0299c0c
Jan  6 20:06:23 eser kernel: [19365.563014]  e0359240 00000600 00001000
00001000 f3a83dfc f828d6da 00000600 00001008
Jan  6 20:06:23 eser kernel: [19365.563014]  00000002 00000000 00000002
00002000 00001608 f3a83ed0 f828e1ff 00001608
Jan  6 20:06:23 eser kernel: [19365.563014] Call Trace:
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c022998e>] ?
__kmap_atomic+0xe/0x10
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c0299c0c>] ?
iov_iter_copy_from_user_atomic+0x3c/0x90
Jan  6 20:06:23 eser kernel: [19365.563014]  [<f828d6da>] ?
btrfs_copy_from_user+0x5a/0xb0 [btrfs]
Jan  6 20:06:23 eser kernel: [19365.563014]  [<f828e1ff>] ?
btrfs_file_aio_write+0x52f/0x9c0 [btrfs]
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d0810>] ?
__mem_cgroup_commit_charge+0x70/0xe0
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d672c>] ?
do_sync_write+0x9c/0xd0
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d6b15>] ?
rw_verify_area+0x65/0x100
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d6e7a>] ?
vfs_write+0x9a/0x160
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d8211>] ?
fget_light+0x91/0xb0
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d6690>] ?
do_sync_write+0x0/0xd0
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d714d>] ? sys_write+0x3d/0x70
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c0202e18>] ?
sysenter_do_call+0x12/0x28
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c04e0000>] ?
quirk_amd_ide_mode+0x40/0x95
Jan  6 20:06:23 eser kernel: [19365.563014] Code: 8b 15 4c 6a 6b c0 55 89 e5 e8
e2 f8 ff ff 5d c3 55 89 e5 83 ec 10 89 e1 81 e1 00 e0 ff ff 89 5d f4 89 75 f8
89 7d fc 83 41 14 01 <8b> 08 c1 e9 1e 69 d9 40 03 00 00 8d 8b c0 42 64 c0 2b 8b
cc 45 
Jan  6 20:06:23 eser kernel: [19365.563014] EIP: [<c022989b>]
kmap_atomic_prot+0x1b/0x100 SS:ESP 0068:f3a83da8
Jan  6 20:06:23 eser kernel: [19365.563014] CR2: 0000000000000000
Jan  6 20:06:23 eser kernel: [19365.568714] ---[ end trace afc2be06c7d06a71
]---
Jan  6 20:06:23 eser kernel: [19365.568724] note: gimp-2.6[15675] exited with
Quoted 4 lines

preempt_count 2
___

The kernel is an unpatched v2.6.37. I have not seen something like this before.

Bugzilla's habit of wordwrapping oops traces is fantastically irritating. Please use attachments to avoid this.

Either Peter's new kmap_atomic() stuff blew up or BTRFS is playing around with a NULL page*. I'd wager on the latter.

Thanks, I'll ask Rafael and Maciej to track this as a 2.6.36->2.6.37 regression.

#3 lore raw

I have checked latest mkfs code. If page size is 4k. sector size will be 4k too. So at least for x86 hardware, page size and sector size will always be the same.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Zhong, Xin
Sent: Friday, January 07, 2011 12:15 PM
To: Andrew Morton; [email protected]
Cc: [email protected]; Peter Zijlstra; [email protected]; [email protected]
Subject: RE: [Bug 26242] New: BUG: unable to handle kernel NULL pointer dereference at (null)

A similar bug has been reported by Kenneth Lakin [[email protected]] last week. It's related to my check-in (git commit 914ee295af418e936ec20a08c1663eaabe4cd07a). I am looking into it now.

I found one suspicious code in prepage_pages (fs/btrfs/file.c):

        start_pos = pos & ~((u64)root->sectorsize - 1);
        last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;

root->sectorsize is used at first, but PAGE_SIZE is used after it. Do we assume these two values are always the same?

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Andrew Morton
Sent: Friday, January 07, 2011 5:13 AM
To: [email protected]
Cc: [email protected]; Peter Zijlstra; [email protected]; [email protected]
Subject: Re: [Bug 26242] New: BUG: unable to handle kernel NULL pointer dereference at (null)

(switched to email. Please respond via emailed reply-to-all, not via the bugzilla web interface).

Quoted 107 lines · On Thu, 6 Jan 2011 20:59:08 GMT [email protected] wrote:

https://bugzilla.kernel.org/show_bug.cgi?id=26242

Summary: BUG: unable to handle kernel NULL pointer dereference
at (null)
Product: Memory Management
Version: 2.5
Kernel Version: 2.6.37
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: low
Priority: P1
Component: Other
AssignedTo: [email protected]
ReportedBy: [email protected]
Regression: No

My system crashed with the following output:

___

Jan  6 20:06:22 eser kernel: [19365.562621] BUG: unable to handle kernel NULL
pointer dereference at   (null)
Jan  6 20:06:22 eser kernel: [19365.562675] IP: [<c022989b>]
kmap_atomic_prot+0x1b/0x100
Jan  6 20:06:22 eser kernel: [19365.562709] *pde = 00000000 
Jan  6 20:06:22 eser kernel: [19365.562726] Oops: 0000 [#1] PREEMPT SMP 
Jan  6 20:06:22 eser kernel: [19365.562752] last sysfs file:
/sys/devices/platform/coretemp.0/temp1_input
Jan  6 20:06:22 eser kernel: [19365.562777] Modules linked in: isofs usblp

usb_storage uas nls_utf8 udf crc_itu_t fuse ipt_MASQUERADE xt_pkttype xt_TCPMSS xt_tcpudp ipt_LOG xt_limit iptable_nat nf_nat snd_pcm_oss snd_mixer_oss snd_seq snd_seq_device xt_NOTRACK ipt_REJECT xt_state iptable_raw iptable_filter nf_conntrack_netbios_ns nf_conntrack_ipv4 nf_conntrack nf_defrag_ipv4 ip_tables cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq mperf speedstep_lib ip6_tables x_tables loop arc4 ecb b43 snd_hda_codec_si3054 mac80211 snd_hda_codec_realtek snd_hda_intel r8169 snd_hda_codec cfg80211 sdhci_pci mii snd_hwdep acer_wmi sdhci snd_pcm rfkill iTCO_wdt yenta_socket ssb tifm_7xx1 iTCO_vendor_support sg sr_mod mmc_core snd_timer pcmcia_core tifm_core cdrom pcspkr wmi pcmcia_rsrc psmouse snd i2c_i801 shpchp evdev soundcore battery rng_core ac snd_page_alloc pci_hotplug dm_crypt usbhid hid nouveau ttm drm_kms_helper drm uhci_hcd rtc_cmos ata_piix i2c_algo_bit i2c_core rtc_core cfbcopyarea ehci_hcd usb

Jan  6 20:06:22 eser kernel: core video cfbimgblt cfbfillrect rtc_lib output

button nls_base dm_snapshot sha512_generic sha256_generic xts cbc aes_i586 aes_generic cfq_iosched blk_cgroup btrfs zlib_deflate libcrc32c reiserfs ahci libahci libata coretemp hwmon fan thermal processor unix [last unloaded:
pktcdvd]

Jan  6 20:06:22 eser kernel: [19365.563014] 
Jan  6 20:06:22 eser kernel: [19365.563014] Pid: 15675, comm: gimp-2.6 Not
tainted 2.6.37 #1 Myall2                         /Aspire 9410
Jan  6 20:06:22 eser kernel: [19365.563014] EIP: 0060:[<c022989b>] EFLAGS:
00010202 CPU: 0
Jan  6 20:06:22 eser kernel: [19365.563014] EIP is at
kmap_atomic_prot+0x1b/0x100
Jan  6 20:06:22 eser kernel: [19365.563014] EAX: 00000000 EBX: 00000600 ECX:
f3a82000 EDX: 00000163
Jan  6 20:06:23 eser kernel: [19365.563014] ESI: f3a83eac EDI: 00000000 EBP:
f3a83db8 ESP: f3a83da8
Jan  6 20:06:23 eser kernel: [19365.563014]  DS: 007b ES: 007b FS: 00d8 GS:
0033 SS: 0068
Jan  6 20:06:23 eser kernel: [19365.563014] Process gimp-2.6 (pid: 15675,
ti=f3a82000 task=eaf28000 task.ti=f3a82000)
Jan  6 20:06:23 eser kernel: [19365.563014] Stack:
Jan  6 20:06:23 eser kernel: [19365.563014]  f3a83dc0 00000600 f3a83eac
00000000 f3a83dc0 c022998e f3a83dd8 c0299c0c
Jan  6 20:06:23 eser kernel: [19365.563014]  e0359240 00000600 00001000
00001000 f3a83dfc f828d6da 00000600 00001008
Jan  6 20:06:23 eser kernel: [19365.563014]  00000002 00000000 00000002
00002000 00001608 f3a83ed0 f828e1ff 00001608
Jan  6 20:06:23 eser kernel: [19365.563014] Call Trace:
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c022998e>] ?
__kmap_atomic+0xe/0x10
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c0299c0c>] ?
iov_iter_copy_from_user_atomic+0x3c/0x90
Jan  6 20:06:23 eser kernel: [19365.563014]  [<f828d6da>] ?
btrfs_copy_from_user+0x5a/0xb0 [btrfs]
Jan  6 20:06:23 eser kernel: [19365.563014]  [<f828e1ff>] ?
btrfs_file_aio_write+0x52f/0x9c0 [btrfs]
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d0810>] ?
__mem_cgroup_commit_charge+0x70/0xe0
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d672c>] ?
do_sync_write+0x9c/0xd0
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d6b15>] ?
rw_verify_area+0x65/0x100
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d6e7a>] ?
vfs_write+0x9a/0x160
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d8211>] ?
fget_light+0x91/0xb0
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d6690>] ?
do_sync_write+0x0/0xd0
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d714d>] ? sys_write+0x3d/0x70
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c0202e18>] ?
sysenter_do_call+0x12/0x28
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c04e0000>] ?
quirk_amd_ide_mode+0x40/0x95
Jan  6 20:06:23 eser kernel: [19365.563014] Code: 8b 15 4c 6a 6b c0 55 89 e5 e8
e2 f8 ff ff 5d c3 55 89 e5 83 ec 10 89 e1 81 e1 00 e0 ff ff 89 5d f4 89 75 f8
89 7d fc 83 41 14 01 <8b> 08 c1 e9 1e 69 d9 40 03 00 00 8d 8b c0 42 64 c0 2b 8b
cc 45 
Jan  6 20:06:23 eser kernel: [19365.563014] EIP: [<c022989b>]
kmap_atomic_prot+0x1b/0x100 SS:ESP 0068:f3a83da8
Jan  6 20:06:23 eser kernel: [19365.563014] CR2: 0000000000000000
Jan  6 20:06:23 eser kernel: [19365.568714] ---[ end trace afc2be06c7d06a71
]---
Jan  6 20:06:23 eser kernel: [19365.568724] note: gimp-2.6[15675] exited with
Quoted 4 lines

preempt_count 2
___

The kernel is an unpatched v2.6.37. I have not seen something like this before.

Bugzilla's habit of wordwrapping oops traces is fantastically irritating. Please use attachments to avoid this.

Either Peter's new kmap_atomic() stuff blew up or BTRFS is playing around with a NULL page*. I'd wager on the latter.

Thanks, I'll ask Rafael and Maciej to track this as a 2.6.36->2.6.37 regression.

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#4 lore raw

I believe below check-in will fix this problem. Thanks for Yan Zheng's help!

http://www.spinics.net/lists/linux-btrfs/msg08051.html

-----Original Message-----
From: Zhong, Xin
Sent: Friday, January 07, 2011 2:46 PM
To: Zhong, Xin; Andrew Morton; [email protected]
Cc: [email protected]; Peter Zijlstra; [email protected]; [email protected]
Subject: RE: [Bug 26242] New: BUG: unable to handle kernel NULL pointer dereference at (null)

I have checked latest mkfs code. If page size is 4k. sector size will be 4k too. So at least for x86 hardware, page size and sector size will always be the same.

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Zhong, Xin
Sent: Friday, January 07, 2011 12:15 PM
To: Andrew Morton; [email protected]
Cc: [email protected]; Peter Zijlstra; [email protected]; [email protected]
Subject: RE: [Bug 26242] New: BUG: unable to handle kernel NULL pointer dereference at (null)

A similar bug has been reported by Kenneth Lakin [[email protected]] last week. It's related to my check-in (git commit 914ee295af418e936ec20a08c1663eaabe4cd07a). I am looking into it now.

I found one suspicious code in prepage_pages (fs/btrfs/file.c):

        start_pos = pos & ~((u64)root->sectorsize - 1);
        last_pos = ((u64)index + num_pages) << PAGE_CACHE_SHIFT;

root->sectorsize is used at first, but PAGE_SIZE is used after it. Do we assume these two values are always the same?

-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Andrew Morton
Sent: Friday, January 07, 2011 5:13 AM
To: [email protected]
Cc: [email protected]; Peter Zijlstra; [email protected]; [email protected]
Subject: Re: [Bug 26242] New: BUG: unable to handle kernel NULL pointer dereference at (null)

(switched to email. Please respond via emailed reply-to-all, not via the bugzilla web interface).

Quoted 107 lines · On Thu, 6 Jan 2011 20:59:08 GMT [email protected] wrote:

https://bugzilla.kernel.org/show_bug.cgi?id=26242

Summary: BUG: unable to handle kernel NULL pointer dereference
at (null)
Product: Memory Management
Version: 2.5
Kernel Version: 2.6.37
Platform: All
OS/Version: Linux
Tree: Mainline
Status: NEW
Severity: low
Priority: P1
Component: Other
AssignedTo: [email protected]
ReportedBy: [email protected]
Regression: No

My system crashed with the following output:

___

Jan  6 20:06:22 eser kernel: [19365.562621] BUG: unable to handle kernel NULL
pointer dereference at   (null)
Jan  6 20:06:22 eser kernel: [19365.562675] IP: [<c022989b>]
kmap_atomic_prot+0x1b/0x100
Jan  6 20:06:22 eser kernel: [19365.562709] *pde = 00000000 
Jan  6 20:06:22 eser kernel: [19365.562726] Oops: 0000 [#1] PREEMPT SMP 
Jan  6 20:06:22 eser kernel: [19365.562752] last sysfs file:
/sys/devices/platform/coretemp.0/temp1_input
Jan  6 20:06:22 eser kernel: [19365.562777] Modules linked in: isofs usblp

usb_storage uas nls_utf8 udf crc_itu_t fuse ipt_MASQUERADE xt_pkttype xt_TCPMSS xt_tcpudp ipt_LOG xt_limit iptable_nat nf_nat snd_pcm_oss snd_mixer_oss snd_seq snd_seq_device xt_NOTRACK ipt_REJECT xt_state iptable_raw iptable_filter nf_conntrack_netbios_ns nf_conntrack_ipv4 nf_conntrack nf_defrag_ipv4 ip_tables cpufreq_conservative cpufreq_userspace cpufreq_powersave acpi_cpufreq mperf speedstep_lib ip6_tables x_tables loop arc4 ecb b43 snd_hda_codec_si3054 mac80211 snd_hda_codec_realtek snd_hda_intel r8169 snd_hda_codec cfg80211 sdhci_pci mii snd_hwdep acer_wmi sdhci snd_pcm rfkill iTCO_wdt yenta_socket ssb tifm_7xx1 iTCO_vendor_support sg sr_mod mmc_core snd_timer pcmcia_core tifm_core cdrom pcspkr wmi pcmcia_rsrc psmouse snd i2c_i801 shpchp evdev soundcore battery rng_core ac snd_page_alloc pci_hotplug dm_crypt usbhid hid nouveau ttm drm_kms_helper drm uhci_hcd rtc_cmos ata_piix i2c_algo_bit i2c_core rtc_core cfbcopyarea ehci_hcd usb

Jan  6 20:06:22 eser kernel: core video cfbimgblt cfbfillrect rtc_lib output

button nls_base dm_snapshot sha512_generic sha256_generic xts cbc aes_i586 aes_generic cfq_iosched blk_cgroup btrfs zlib_deflate libcrc32c reiserfs ahci libahci libata coretemp hwmon fan thermal processor unix [last unloaded:
pktcdvd]

Jan  6 20:06:22 eser kernel: [19365.563014] 
Jan  6 20:06:22 eser kernel: [19365.563014] Pid: 15675, comm: gimp-2.6 Not
tainted 2.6.37 #1 Myall2                         /Aspire 9410
Jan  6 20:06:22 eser kernel: [19365.563014] EIP: 0060:[<c022989b>] EFLAGS:
00010202 CPU: 0
Jan  6 20:06:22 eser kernel: [19365.563014] EIP is at
kmap_atomic_prot+0x1b/0x100
Jan  6 20:06:22 eser kernel: [19365.563014] EAX: 00000000 EBX: 00000600 ECX:
f3a82000 EDX: 00000163
Jan  6 20:06:23 eser kernel: [19365.563014] ESI: f3a83eac EDI: 00000000 EBP:
f3a83db8 ESP: f3a83da8
Jan  6 20:06:23 eser kernel: [19365.563014]  DS: 007b ES: 007b FS: 00d8 GS:
0033 SS: 0068
Jan  6 20:06:23 eser kernel: [19365.563014] Process gimp-2.6 (pid: 15675,
ti=f3a82000 task=eaf28000 task.ti=f3a82000)
Jan  6 20:06:23 eser kernel: [19365.563014] Stack:
Jan  6 20:06:23 eser kernel: [19365.563014]  f3a83dc0 00000600 f3a83eac
00000000 f3a83dc0 c022998e f3a83dd8 c0299c0c
Jan  6 20:06:23 eser kernel: [19365.563014]  e0359240 00000600 00001000
00001000 f3a83dfc f828d6da 00000600 00001008
Jan  6 20:06:23 eser kernel: [19365.563014]  00000002 00000000 00000002
00002000 00001608 f3a83ed0 f828e1ff 00001608
Jan  6 20:06:23 eser kernel: [19365.563014] Call Trace:
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c022998e>] ?
__kmap_atomic+0xe/0x10
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c0299c0c>] ?
iov_iter_copy_from_user_atomic+0x3c/0x90
Jan  6 20:06:23 eser kernel: [19365.563014]  [<f828d6da>] ?
btrfs_copy_from_user+0x5a/0xb0 [btrfs]
Jan  6 20:06:23 eser kernel: [19365.563014]  [<f828e1ff>] ?
btrfs_file_aio_write+0x52f/0x9c0 [btrfs]
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d0810>] ?
__mem_cgroup_commit_charge+0x70/0xe0
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d672c>] ?
do_sync_write+0x9c/0xd0
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d6b15>] ?
rw_verify_area+0x65/0x100
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d6e7a>] ?
vfs_write+0x9a/0x160
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d8211>] ?
fget_light+0x91/0xb0
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d6690>] ?
do_sync_write+0x0/0xd0
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c02d714d>] ? sys_write+0x3d/0x70
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c0202e18>] ?
sysenter_do_call+0x12/0x28
Jan  6 20:06:23 eser kernel: [19365.563014]  [<c04e0000>] ?
quirk_amd_ide_mode+0x40/0x95
Jan  6 20:06:23 eser kernel: [19365.563014] Code: 8b 15 4c 6a 6b c0 55 89 e5 e8
e2 f8 ff ff 5d c3 55 89 e5 83 ec 10 89 e1 81 e1 00 e0 ff ff 89 5d f4 89 75 f8
89 7d fc 83 41 14 01 <8b> 08 c1 e9 1e 69 d9 40 03 00 00 8d 8b c0 42 64 c0 2b 8b
cc 45 
Jan  6 20:06:23 eser kernel: [19365.563014] EIP: [<c022989b>]
kmap_atomic_prot+0x1b/0x100 SS:ESP 0068:f3a83da8
Jan  6 20:06:23 eser kernel: [19365.563014] CR2: 0000000000000000
Jan  6 20:06:23 eser kernel: [19365.568714] ---[ end trace afc2be06c7d06a71
]---
Jan  6 20:06:23 eser kernel: [19365.568724] note: gimp-2.6[15675] exited with
Quoted 4 lines

preempt_count 2
___

The kernel is an unpatched v2.6.37. I have not seen something like this before.

Bugzilla's habit of wordwrapping oops traces is fantastically irritating. Please use attachments to avoid this.

Either Peter's new kmap_atomic() stuff blew up or BTRFS is playing around with a NULL page*. I'd wager on the latter.

Thanks, I'll ask Rafael and Maciej to track this as a 2.6.36->2.6.37 regression.

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