2.6.24.2: 4KSTACKS + PCA403CD IDE CD + pcdrw + mount + PREEMPT -> stack overflow

2.6.24.2: 4KSTACKS + PCA403CD IDE CD + pcdrw + mount + PREEMPT -> stack overflow

[Nix]

A loop mount/umounting a pcdrw or iso9660 (through the pktcdvd device)
sees a stack overflow in four or five tries. Doing the same thing with
the same CD in a normal non-pktcdvd-mounted drive doesn't cause a crash.

Here's a couple of oopses. config follows.

(There are a wide variety. Some I couldn't collect because they appeared
to recurse, blurring past much too fast to read. Some simply didn't go
out of the netconsole logger at all for no obvious reason.)

(This may or may not be PREEMPT+PREEMPT_BKL-specific: I'll try turning
them off tomorrow and repeating.)

(The presence of dm in the first oops below must surely be attributed to
preempt: certainly my CD isn't managed by dm :) )

pktcdvd: Fixed packets, 32 blocks, Mode-2 disc
pktcdvd: Max. media speed: 4
pktcdvd: write speed 2x
pktcdvd: 551232kB available on disc
UDF-fs INFO UDF 0.9.8.1 (2004/29/09) Mounting volume 'LinuxUDF', timestamp 2004/02/09 07:10 (1000)
do_IRQ: stack overflow: 480
Pid: 4645, comm: mount Not tainted 2.6.24.2-dirty #4
 [<c0104171>] do_IRQ+0x66/0xc5
 [<c0102f8b>] common_interrupt+0x23/0x28
 [<c027b5da>] ide_outsl+0x5/0x9
 [<c027c540>] ata_output_data+0x4d/0x64
 [<c027b8a6>] atapi_output_bytes+0x19/0x3f
 [<c0285377>] cdrom_transfer_packet_command+0xb5/0xde
 [<c0282607>] cdrom_timer_expiry+0x0/0x51
 [<c02840c3>] cdrom_start_packet_command+0x14f/0x157
 [<c02853e9>] cdrom_do_pc_continuation+0x0/0x2c
 [<c027aa33>] ide_do_request+0x70a/0x943
 [<c0363ef3>] schedule_timeout+0x13/0x8b
 [<c021faeb>] elv_drain_elevator+0x15/0x58
 [<c0220277>] elv_insert+0xf6/0x1d9
 [<c0285377>] cdrom_transfer_packet_command+0xb5/0xde
 [<c0282607>] cdrom_timer_expiry+0x0/0x51
 [<c027b038>] ide_do_drive_cmd+0x99/0xe9
 [<c0282abe>] cdrom_queue_packet_command+0x35/0xa9
 [<c0363b2b>] schedule+0x321/0x33e
 [<c0363ef3>] schedule_timeout+0x13/0x8b
 [<c0282d11>] cdrom_read_tocentry+0x96/0xa1
 [<c02220d3>] blk_end_sync_rq+0x0/0x23
 [<c028315b>] cdrom_read_toc+0x14b/0x42e
 [<c02220d3>] blk_end_sync_rq+0x0/0x23
 [<c027b07e>] ide_do_drive_cmd+0xdf/0xe9
 [<c0283ed2>] ide_cdrom_audio_ioctl+0x13c/0x1de
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0282f42>] cdrom_check_status+0x55/0x60
 [<c02220d3>] blk_end_sync_rq+0x0/0x23
 [<c02865ba>] cdrom_count_tracks+0x64/0x16a
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c02896c4>] cdrom_open+0x190/0x8f8
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c02252d3>] get_disk+0x4e/0x65
 [<c02252f1>] exact_lock+0x7/0xd
 [<c025a2cc>] kobj_lookup+0x104/0x12e
 [<c02828e8>] idecd_open+0x72/0x86
 [<c0174458>] do_open+0x198/0x238
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c0174561>] __blkdev_get+0x69/0x74
 [<c017457e>] blkdev_get+0x12/0x14
 [<c0263333>] pkt_open+0x8d/0xc96
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c022998c>] kobject_get+0xf/0x13
 [<c02252d3>] get_disk+0x4e/0x65
 [<c02252f1>] exact_lock+0x7/0xd
 [<c025a2cc>] kobj_lookup+0x104/0x12e
 [<c0224ed0>] exact_match+0x0/0x4
 [<c0174344>] do_open+0x84/0x238
 [<c0174561>] 
EIP: 0060:[<c01033d2>] EFLAGS: 00010093 CPU: 0
EIP is at dump_trace+0x52/0x8b
EAX: 0000082a EBX: 00000046 ECX: 0000020a EDX: 00000000
ESI: 00000000 EDI: 00000000 EBP: 00000ffc ESP: eeede1c4
 DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068
rocess mount (pid: 4645, ti=eeede000 task=ee537320 task.ti=eeede000)v<tack:  00001000 c03f6c0c 00000000 c0523b64 00000000 c0103423 c036e79c c03f6c0c 
       00000002 c0103bf2 c03f6c0c c0103f85 c03ccd19 00001225 ee5375d0 c0505178 
       c0429436 00000002 c0429477 eeede220 0000000d c0104171 c03cce23 000001e0 
Call Trace:
 [<c0103423>] show_trace_log_lvl+0x18/0x2c
 [<c0103bf2>] show_trace+0xf/0x11
 [<c0103f85>] dump_stack+0x68/0x6d
 [<c0104171>] do_IRQ+0x66/0xc5
 [<c0102f8b>] common_interrupt+0x23/0x28
 [<c027b5da>] ide_outsl+0x5/0x9
 [<c027c540>] ata_output_data+0x4d/0x64
 [<c027b8a6>] atapi_output_bytes+0x19/0x3f
 [<c0285377>] cdrom_transfer_packet_command+0xb5/0xde
 [<c0282607>] cdrom_timer_expiry+0x0/0x51
 [<c02840c3>] cdrom_start_packet_command+0x14f/0x157
 [<c02853e9>] cdrom_do_pc_continuation+0x0/0x2c
 [<c027aa33>] ide_do_request+0x70a/0x943
 [<c0363ef3>] schedule_timeout+0x13/0x8b
 [<c021faeb>] elv_drain_elevator+0x15/0x58
 [<c0220277>] elv_insert+0xf6/0x1d9
 [<c0285377>] cdrom_transfer_packet_command+0xb5/0xde
 [<c0282607>] cdrom_timer_expiry+0x0/0x51
 [<c027b038>] ide_do_drive_cmd+0x99/0xe9
 [<c0282abe>] cdrom_queue_packet_command+0x35/0xa9
 [<c0363b2b>] schedule+0x321/0x33e
 [<c0363ef3>] schedule_timeout+0x13/0x8b
 [<c0282d11>] cdrom_read_tocentry+0x96/0xa1
 [<c02220d3>] blk_end_sync_rq+0x0/0x23
 [<c028315b>] cdrom_read_toc+0x14b/0x42e
 [<c02220d3>] blk_end_sync_rq+0x0/0x23
 [<c027b07e>] ide_do_drive_cmd+0xdf/0xe9
 [<c0283ed2>] ide_cdrom_audio_ioctl+0x13c/0x1de
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0282f42>] cdrom_check_status+0x55/0x60
 [<c02220d3>] blk_end_sync_rq+0x0/0x23
 [<c02865ba>] cdrom_count_tracks+0x64/0x16a
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c02896c4>] cdrom_open+0x190/0x8f8
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c02252d3>] get_disk+0x4e/0x65
 [<c02252f1>] exact_lock+0x7/0xd
 [<c025a2cc>] kobj_lookup+0x104/0x12e
 [<c02828e8>] idecd_open+0x72/0x86
 [<c0174458>] do_open+0x198/0x238
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c0174561>] __blkdev_get+0x69/0x74
 [<c017457e>] blkdev_get+0x12/0x14
 [<c0263333>] pkt_open+0x8d/0xc96
 [<c017162c>] dump_trace+0x52/0x8b
 [<c0103423>] show_trace_log_lvl+0x18/0x2c
 [<c0103bf2>] show_trace+0xf/0x11
 [<c0103f85>] dump_stack+0x68/0x6d
 [<c0104171>] do_IRQ+0x66/0xc5
 [<c0102f8b>] common_interrupt+0x23/0x28
 [<c027b5da>] ide_outsl+0x5/0x9
 [<c027c540>] ata_output_data+0x4d/0x64
 [<c027b8a6>] atapi_output_bytes+0x19/0x3f
 [<c0285377>] cdrom_transfer_packet_command+0xb5/0xde
 [<c0282607>] cdrom_timer_expiry+0x0/0x51
 [<c02840c3>] cdrom_start_packet_command+0x14f/0x157
 [<c02853e9>] cdrom_do_pc_continuation+0x0/0x2c
 [<c027aa33>] ide_do_request+0x70a/0x943
 [<c0363ef3>] schedule_timeout+0x13/0x8b
 [<c021faeb>] elv_drain_elevator+0x15/0x58
 [<c0220277>] elv_insert+0xf6/0x1d9
 [<c0285377>] cdrom_transfer_packet_command+0xb5/0xde
 [<c0282607>] cdrom_timer_expiry+0x0/0x51
 [<c027b038>] ide_do_drive_cmd+0x99/0xe9
 [<c0282abe>] cdrom_queue_packet_command+0x35/0xa9
 [<c0363b2b>] schedule+0x321/0x33e
 [<c0363ef3>] schedule_timeout+0x13/0x8b
 [<c0282d11>] cdrom_read_tocentry+0x96/0xa1
 [<c02220d3>] blk_end_sync_rq+0x0/0x23
 [<c028315b>] cdrom_read_toc+0x14b/0x42e
 [<c02220d3>] blk_end_sync_rq+0x0/0x23
 [<c027b07e>] ide_do_drive_cmd+0xdf/0xe9
 [<c0283ed2>] ide_cdrom_audio_ioctl+0x13c/0x1de
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0282f42>] cdrom_check_status+0x55/0x60
 [<c02220d3>] blk_end_sync_rq+0x0/0x23
 [<c02865ba>] cdrom_count_tracks+0x64/0x16a
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c02896c4>] cdrom_open+0x190/0x8f8
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c02afbd9>] console [netcon0] enabled


Second oops:

netconsole: network logging started
pktcdvd: Fixed packets, 32 blocks, Mode-2 disc
pktcdvd: Max. media speed: 4
pktcdvd: write speed 2x
pktcdvd: 551232kB available on disc
UDF-fs INFO UDF 0.9.8.1 (2004/29/09) Mounting volume 'LinuxUDF', timestamp 2004/05/03 13:03 (1000)
do_IRQ: stack overflow: 388
Pid: 1515, comm: mount Not tainted 2.6.24.2-dirty #4
 [<c0104171>] do_IRQ+0x66/0xc5
 [<c027c540>] ata_output_data+0x4d/0x64
 [<c0102f8b>] common_interrupt+0x23/0x28
 [<c027c60d>] ide_outb+0x1/0x2
 [<c0284015>] cdrom_start_packet_command+0xa1/0x157
 [<c02853e9>] cdrom_do_pc_continuation+0x0/0x2c
 [<c027aa33>] ide_do_request+0x70a/0x943
 [<c0363ef3>] schedule_timeout+0x13/0x8b
 [<c0363ef3>] schedule_timeout+0x13/0x8b
 [<c027c540>] ata_output_data+0x4d/0x64
 [<c021faeb>] elv_drain_elevator+0x15/0x58
 [<c0220277>] elv_insert+0xf6/0x1d9
 [<c0363d78>] wait_for_common+0xb6/0x12f
 [<c0221ee4>] __blk_put_request+0x1e/0x6f
 [<c027b038>] ide_do_drive_cmd+0x99/0xe9
 [<c0282abe>] cdrom_queue_packet_command+0x35/0xa9
 [<c0282abe>] cdrom_queue_packet_command+0x35/0xa9
 [<c0363ef3>] schedule_timeout+0x13/0x8b
 [<c0285b5b>] ide_cdrom_packet+0x80/0xa1
 [<c02220d3>] blk_end_sync_rq+0x0/0x23
 [<c0286be0>] cdrom_get_track_info+0x91/0x9e
 [<c0286c49>] cdrom_get_last_written+0x5c/0x107
 [<c02220d3>] blk_end_sync_rq+0x0/0x23
 [<c02833f7>] cdrom_read_toc+0x3e7/0x42e
 [<c02220d3>] blk_end_sync_rq+0x0/0x23
 [<c0283ed2>] ide_cdrom_audio_ioctl+0x13c/0x1de
 [<c0282f42>] cdrom_check_status+0x55/0x60
 [<c02220d3>] blk_end_sync_rq+0x0/0x23
 [<c02865ba>] cdrom_count_tracks+0x64/0x16a
 [<c02896c4>] cdrom_open+0x190/0x8f8
 [<c02252d3>] get_disk+0x4e/0x65
 [<c02252f1>] exact_lock+0x7/0xd
 [<c025a2cc>] kobj_lookup+0x104/0x12e
 [<c02828e8>] idecd_open+0x72/0x86
 [<c0174458>] do_open+0x198/0x238
 [<c0174561>] __blkdev_get+0x69/0x74
 [<c017457e>]  [<c02252d3>] get_disk+0x4e/0x65
 [<c02252f1>] exact_lock+0x7/0xd
 [<c025a2cc>] kobj_lookup+0x104/0x12e
 [<c0224ed0>] exact_match+0x0/0x4
 [<c0174344>] do_open+0x84/0x238
 [<c0174561>] __blkdev_get+0x69/0x74
 [<c017457e>] blkdev_get+0x12/0x14
 [<c0174894>] open_bdev_excl+0x2b/0x65
 [<c0155f20>] get_sb_bdev+0x14/0x108
 [<c021182c>] udf_get_sb+0x20/0x25
 [<c0213197>] udf_fill_super+0x0/0xb63
 [<c0155e04>] vfs_kern_mount+0x40/0x79
 [<c0155e86>] do_kern_mount+0x35/0xbb
 [<c0167b7d>] do_mount+0x5da/0x621
 [<c01669e9>] mntput_no_expire+0x13/0x7c
 [<c015c6a4>] link_path_walk+0xa5/0xaf
 [<c01445e9>] handle_mm_fault+0x263/0x531
 [<c01383b8>] find_lock_page+0x1f/0x96
 [<c013a485>] filemap_fault+0x21d/0x37d
 [<c015d140>] __user_walk_fd+0x3d/0x45
 [<c013cb08>] __alloc_pages+0x5d/0x2d9
 [<c013cdb6>] __get_free_pages+0x32/0x4d
 [<c0166669>] copy_mount_options+0x26/0x10d
 [<c0167c3b>] sys_mount+0x77/0xb3
 [<c010257a>] sysenter_past_esp+0x5f/0x85
 [<c031ffff>] __ip_route_output_key+0x257/0x733
BUG: unable to handle kernel paging request at virtual address 83c70a74
printing eip: c01033d2 *pde = 00000000 
Oops: 0000 [#1] PREEMPT 
Modules linked in: netconsole

Pid: 1515, comm: mount Not tainted (2.6.24.2-dirty #4)
EIP: 0060:[<c01033d2>] EFLAGS: 00010097 CPU: 0
EIP is at dump_trace+0x52/0x8b
EAX: 00000114 EBX: 83c70a74 ECX: 00000045 EDX: 00000000
ESI: 470a2c47 EDI: 83c70000 EBP: 83c70ffc ESP: ee401168
 DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068
Process mount (pid: 1515, ti=ee401000 task=eef86680 task.ti=ee401000)
Stack: 63736e2f c03f6c0c 00000000 0000001c 00000000 c0103423 c036e79c c03f6c0c 
       00000002 c0103bf2 c03f6c0c c0103f85 c03ccd19 000005eb eef86930 c0505178 
       c0429436 00000002 c0429477 ee4011c4 c0523bbc c0104171 c03cce23 00000184 
Call Trace:
 [<c0103423>] show_trace_log_lvl+0x18/0x2c
 [<c0103bf2>] show_trace+0xf/0x11
 [<c0103f85>] dump_stack+0x68/0x6d
 [<c0104171>] do_IRQ+0x66/0xc5
 [<c027c540>] ata_output_data+0x4d/0x64
 [<c0102f8b>] common_interrupt+0x23/0x28
 [<c027c60d>] ide_outb+0x1/0x2
 [<c0284015>] cdrom_start_packet_command+0xa1/0x157
 [<c02853e9>] cdrom_do_pc_continuation+0x0/0x2c
 [<c027aa33>] ide_do_request+0x70a/0x943
 [<c0363ef3>] schedule_timeout+0x13/0x8b
 [<c0363ef3>] schedule_timeout+0x13/0x8b
 [<c027c540>] ata_output_data+0x4d/0x64
 [<c021faeb>] elv_drain_elevator+0x15/0x58
 [<c0220277>] elv_insert+0xf6/0x1d9
 [<c0363d78>] wait_for_common+0xb6/0x12f
 [<c0221ee4>] __blk_put_request+0x1e/0x6f
 [<c027b038>] ide_do_drive_cmd+0x99/0xe9
idecd_open+0x72/0x86
do_open+0x198/0x238
 [<c0174561>] __blkdev_get+0x69/0x74
 [<c017457e>] blkdev_get+0x12/0x14
 [<c0263333>] pkt_open+0x8d/0xc96
 [<c022998c>] kobject_get+0xf/0x13
 [<c02252d3>] get_disk+0x4e/0x65
 [<c02252f1>] exact_lock+0x7/0xd
 [<c025a2cc>] kobj_lookup+0x104/0x12e
 [<c0224ed0>] exact_match+0x0/0x4
 [<c0174344>] do_open+0x84/0x238
 [<c0174561>] __blkdev_get+0x69/0x74
 [<c017457e>] blkdev_get+0x12/0x14
 [<c0174894>] open_bdev_excl+0x2b/0x65
 [<c0155f20>] get_sb_bdev+0x14/0x108
 [<c021182c>] udf_get_sb+0x20/0x25
 [<c0213197>] udf_fill_super+0x0/0xb63
 [<c0155e04>] vfs_kern_mount+0x40/0x79
 [<c0155e86>] do_kern_mount+0x35/0xbb
 [<c0167b7d>] do_mount+0x5da/0x621
 [<c01669e9>] mntput_no_expire+0x13/0x7c
 [<c015c6a4>] link_path_walk+0xa5/0xaf
 [<c01445e9>] handle_mm_fault+0x263/0x531
 [<c01383b8>] find_lock_page+0x1f/0x96
 [<c013a485>] filemap_fault+0x21d/0x37d
 [<c015d140>] __user_walk_fd+0x3d/0x45
 [<c013cb08>] __alloc_pages+0x5d/0x2d9
 [<c013cdb6>] __get_free_pages+0x32/0x4d
 [<c0166669>] copy_mount_options+0x26/0x10d
 [<c0167c3b>] sys_mount+0x77/0xb3
 [<c010257a>] sysenter_past_esp+0x5f/0x85
 [<c03117eb>] dev_ethtool+0x5f2/0xbdf
BUG: unable to handle kernel paging request at virtual address 0f742024
printing eip: c01033d2 *pde = 00000000 
Recursive die() failure, output suppressed
---[ end trace b1006dcd2ea53f36 ]---
BUG: unable to handle kernel NULL pointer dereference at virtual address 00000069
printing eip: c0116289 *pde = 00000000 
Oops: 0000 [#3] PREEMPT 
Modules linked in: netconsole

Pid: 1515, comm: mount Tainted: G      D (2.6.24.2-dirty #4)
EIP: 0060:[<c0116289>] EFLAGS: 00010246 CPU: 0
EIP is at do_exit+0x20f/0x658
EAX: 00000045 EBX: 00000001 ECX: eef86c78 EDX: 00000000
ESI: eef86680 EDI: 0000000b EBP: 00000046 ESP: ee400e2c
 DS: 007b ES: 007b FS: 0000 GS: 0000 SS: 0068
Process mount (pid: 1515, ti=ee400000 task=eef86680 task.ti=ee401000)
Stack: 00000093 ee400ed0 00000000 c03d103b 00000046 c01141d4 c03d12cf ee400e58 
       ee400e58 ee400ed0 00000000 c03d103b 00000046 c010383d c03cca34 eef3d200 
       eef86680 0f742024 00000000 eef3d200 eef86680 0f742024 c0366770 c03e5efb 
Call Trace:
 [<c01141d4>] printk+0x1b/0x1f
 [<c010383d>] die+0x1a8/0x1b0
 [<c0366770>] do_page_fault+0x502/0x5e2
 [<c036626e>] do_page_fault+0x0/0x5e2
 [<c0365032>] error_code+0x6a/0x70
 [<c01033d2>] dump_trace+0x52/0x8b
 [<c01141d4>] printk+0x1b/0x1f
 [<c0103423>] show_trace_log_lvl+0x18/0x2c
 [<c01034d2>] show_stack_log_lvl+0x9b/0xa3
 [<c0103579>] show_registers+0x9f/0x1bb
 [<c01264ee>] notify_die+0x30/0x34
 [<c0103783>] die+0xee/0x1b0
 [<c0366770>] do_page_fault+0x502/0x5e2
 [<c036626e>] do_page_fault+0x0/0x5e2
 [<c0365032>] error_code+0x6a/0x70
 =======================
Code: 00 89 f0 e8 ae cd 01 00 85 db 74 19 8b 86 


CONFIG_X86_32=y
CONFIG_X86=y
CONFIG_GENERIC_TIME=y
CONFIG_GENERIC_CMOS_UPDATE=y
CONFIG_CLOCKSOURCE_WATCHDOG=y
CONFIG_GENERIC_CLOCKEVENTS=y
CONFIG_GENERIC_CLOCKEVENTS_BROADCAST=y
CONFIG_LOCKDEP_SUPPORT=y
CONFIG_STACKTRACE_SUPPORT=y
CONFIG_SEMAPHORE_SLEEPERS=y
CONFIG_MMU=y
CONFIG_ZONE_DMA=y
CONFIG_QUICKLIST=y
CONFIG_GENERIC_ISA_DMA=y
CONFIG_GENERIC_IOMAP=y
CONFIG_GENERIC_BUG=y
CONFIG_GENERIC_HWEIGHT=y
CONFIG_ARCH_MAY_HAVE_PC_FDC=y
CONFIG_DMI=y
CONFIG_RWSEM_XCHGADD_ALGORITHM=y
CONFIG_GENERIC_CALIBRATE_DELAY=y
CONFIG_ARCH_SUPPORTS_OPROFILE=y
CONFIG_ARCH_POPULATES_NODE_MAP=y
CONFIG_GENERIC_HARDIRQS=y
CONFIG_GENERIC_IRQ_PROBE=y
CONFIG_X86_BIOS_REBOOT=y
CONFIG_KTIME_SCALAR=y
CONFIG_DEFCONFIG_LIST="/lib/modules/$UNAME_RELEASE/.config"
CONFIG_EXPERIMENTAL=y
CONFIG_BROKEN_ON_SMP=y
CONFIG_LOCK_KERNEL=y
CONFIG_INIT_ENV_ARG_LIMIT=32
CONFIG_LOCALVERSION=""
CONFIG_LOCALVERSION_AUTO=y
CONFIG_SWAP=y
CONFIG_SYSVIPC=y
CONFIG_SYSVIPC_SYSCTL=y
CONFIG_POSIX_MQUEUE=y
CONFIG_BSD_PROCESS_ACCT=y
CONFIG_LOG_BUF_SHIFT=14
CONFIG_CGROUPS=y
CONFIG_FAIR_GROUP_SCHED=y
CONFIG_FAIR_CGROUP_SCHED=y
CONFIG_RELAY=y
CONFIG_BLK_DEV_INITRD=y
CONFIG_INITRAMFS_SOURCE="usr/initramfs.hades"
CONFIG_INITRAMFS_ROOT_UID=99
CONFIG_INITRAMFS_ROOT_GID=101
CONFIG_CC_OPTIMIZE_FOR_SIZE=y
CONFIG_SYSCTL=y
CONFIG_UID16=y
CONFIG_SYSCTL_SYSCALL=y
CONFIG_KALLSYMS=y
CONFIG_HOTPLUG=y
CONFIG_PRINTK=y
CONFIG_BUG=y
CONFIG_ELF_CORE=y
CONFIG_BASE_FULL=y
CONFIG_FUTEX=y
CONFIG_ANON_INODES=y
CONFIG_EPOLL=y
CONFIG_SIGNALFD=y
CONFIG_EVENTFD=y
CONFIG_SHMEM=y
CONFIG_VM_EVENT_COUNTERS=y
CONFIG_SLAB=y
CONFIG_SLABINFO=y
CONFIG_RT_MUTEXES=y
CONFIG_BASE_SMALL=0
CONFIG_MODULES=y
CONFIG_MODULE_UNLOAD=y
CONFIG_KMOD=y
CONFIG_BLOCK=y
CONFIG_BLK_DEV_IO_TRACE=y
CONFIG_IOSCHED_NOOP=y
CONFIG_IOSCHED_AS=m
CONFIG_IOSCHED_DEADLINE=m
CONFIG_IOSCHED_CFQ=y
CONFIG_DEFAULT_CFQ=y
CONFIG_DEFAULT_IOSCHED="cfq"
CONFIG_TICK_ONESHOT=y
CONFIG_HIGH_RES_TIMERS=y
CONFIG_GENERIC_CLOCKEVENTS_BUILD=y
CONFIG_X86_PC=y
CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER=y
CONFIG_MK7=y
CONFIG_X86_CMPXCHG=y
CONFIG_X86_L1_CACHE_SHIFT=6
CONFIG_X86_XADD=y
CONFIG_X86_WP_WORKS_OK=y
CONFIG_X86_INVLPG=y
CONFIG_X86_BSWAP=y
CONFIG_X86_POPAD_OK=y
CONFIG_X86_GOOD_APIC=y
CONFIG_X86_INTEL_USERCOPY=y
CONFIG_X86_USE_PPRO_CHECKSUM=y
CONFIG_X86_USE_3DNOW=y
CONFIG_X86_TSC=y
CONFIG_X86_CMOV=y
CONFIG_X86_MINIMUM_CPU_FAMILY=4
CONFIG_HPET_TIMER=y
CONFIG_HPET_EMULATE_RTC=y
CONFIG_PREEMPT=y
CONFIG_PREEMPT_BKL=y
CONFIG_X86_UP_APIC=y
CONFIG_X86_UP_IOAPIC=y
CONFIG_X86_LOCAL_APIC=y
CONFIG_X86_IO_APIC=y
CONFIG_X86_MCE=y
CONFIG_X86_MCE_NONFATAL=y
CONFIG_VM86=y
CONFIG_X86_MSR=m
CONFIG_X86_CPUID=m
CONFIG_NOHIGHMEM=y
CONFIG_PAGE_OFFSET=0xC0000000
CONFIG_PROC_MM=y
CONFIG_ARCH_FLATMEM_ENABLE=y
CONFIG_ARCH_SPARSEMEM_ENABLE=y
CONFIG_ARCH_SELECT_MEMORY_MODEL=y
CONFIG_SELECT_MEMORY_MODEL=y
CONFIG_FLATMEM_MANUAL=y
CONFIG_FLATMEM=y
CONFIG_FLAT_NODE_MEM_MAP=y
CONFIG_SPARSEMEM_STATIC=y
CONFIG_SPLIT_PTLOCK_CPUS=4
CONFIG_ZONE_DMA_FLAG=1
CONFIG_BOUNCE=y
CONFIG_NR_QUICK=1
CONFIG_VIRT_TO_BUS=y
CONFIG_MTRR=y
CONFIG_SECCOMP=y
CONFIG_HZ_1000=y
CONFIG_HZ=1000
CONFIG_PHYSICAL_START=0x100000
CONFIG_PHYSICAL_ALIGN=0x100000
CONFIG_PM=y
CONFIG_PM_LEGACY=y
CONFIG_SUSPEND_UP_POSSIBLE=y
CONFIG_HIBERNATION_UP_POSSIBLE=y
CONFIG_PCI=y
CONFIG_PCI_GOANY=y
CONFIG_PCI_BIOS=y
CONFIG_PCI_DIRECT=y
CONFIG_PCI_DOMAINS=y
CONFIG_ARCH_SUPPORTS_MSI=y
CONFIG_ISA_DMA_API=y
CONFIG_BINFMT_ELF=y
CONFIG_BINFMT_MISC=y
CONFIG_NET=y
CONFIG_PACKET=y
CONFIG_PACKET_MMAP=y
CONFIG_UNIX=y
CONFIG_INET=y
CONFIG_IP_MULTICAST=y
CONFIG_IP_FIB_HASH=y
CONFIG_INET_DIAG=y
CONFIG_INET_TCP_DIAG=y
CONFIG_TCP_CONG_CUBIC=y
CONFIG_DEFAULT_TCP_CONG="cubic"
CONFIG_UEVENT_HELPER_PATH="/sbin/hotplug"
CONFIG_STANDALONE=y
CONFIG_PREVENT_FIRMWARE_BUILD=y
CONFIG_FW_LOADER=y
CONFIG_PARPORT=m
CONFIG_PARPORT_PC=m
CONFIG_PARPORT_1284=y
CONFIG_BLK_DEV=y
CONFIG_BLK_DEV_FD=y
CONFIG_BLK_DEV_LOOP=m
CONFIG_BLK_DEV_CRYPTOLOOP=m
CONFIG_BLK_DEV_NBD=m
CONFIG_CDROM_PKTCDVD=y
CONFIG_CDROM_PKTCDVD_BUFFERS=16
CONFIG_MISC_DEVICES=y
CONFIG_IDE=y
CONFIG_BLK_DEV_IDE=y
CONFIG_BLK_DEV_IDEDISK=y
CONFIG_IDEDISK_MULTI_MODE=y
CONFIG_BLK_DEV_IDECD=y
CONFIG_IDE_GENERIC=y
CONFIG_BLK_DEV_IDEPCI=y
CONFIG_IDEPCI_SHARE_IRQ=y
CONFIG_IDEPCI_PCIBUS_ORDER=y
CONFIG_BLK_DEV_OFFBOARD=y
CONFIG_BLK_DEV_GENERIC=y
CONFIG_BLK_DEV_IDEDMA_PCI=y
CONFIG_BLK_DEV_PDC202XX_NEW=y
CONFIG_BLK_DEV_VIA82CXXX=y
CONFIG_BLK_DEV_IDEDMA=y
CONFIG_IDE_ARCH_OBSOLETE_INIT=y
CONFIG_SCSI=m
CONFIG_SCSI_DMA=y
CONFIG_BLK_DEV_SD=m
CONFIG_SCSI_SCAN_ASYNC=y
CONFIG_SCSI_WAIT_SCAN=m
CONFIG_SCSI_LOWLEVEL=y
CONFIG_MD=y
CONFIG_BLK_DEV_DM=y
CONFIG_DM_CRYPT=y
CONFIG_DM_SNAPSHOT=y
CONFIG_DM_MIRROR=y
CONFIG_DM_ZERO=y
CONFIG_NETDEVICES=y
CONFIG_DUMMY=m
CONFIG_NET_ETHERNET=y
CONFIG_MII=y
CONFIG_NET_VENDOR_3COM=y
CONFIG_VORTEX=y
CONFIG_INPUT=y
CONFIG_INPUT_MOUSEDEV=y
CONFIG_INPUT_MOUSEDEV_PSAUX=y
CONFIG_INPUT_MOUSEDEV_SCREEN_X=1024
CONFIG_INPUT_MOUSEDEV_SCREEN_Y=768
CONFIG_INPUT_JOYDEV=y
CONFIG_INPUT_KEYBOARD=y
CONFIG_KEYBOARD_ATKBD=y
CONFIG_INPUT_MOUSE=y
CONFIG_MOUSE_PS2=y
CONFIG_MOUSE_PS2_ALPS=y
CONFIG_MOUSE_PS2_LOGIPS2PP=y
CONFIG_MOUSE_PS2_SYNAPTICS=y
CONFIG_MOUSE_PS2_LIFEBOOK=y
CONFIG_MOUSE_PS2_TRACKPOINT=y
CONFIG_INPUT_JOYSTICK=y
CONFIG_JOYSTICK_ANALOG=y
CONFIG_INPUT_MISC=y
CONFIG_SERIO=y
CONFIG_SERIO_I8042=y
CONFIG_SERIO_LIBPS2=y
CONFIG_GAMEPORT=y
CONFIG_GAMEPORT_EMU10K1=y
CONFIG_VT=y
CONFIG_VT_CONSOLE=y
CONFIG_HW_CONSOLE=y
CONFIG_SERIAL_8250=y
CONFIG_FIX_EARLYCON_MEM=y
CONFIG_SERIAL_8250_PCI=y
CONFIG_SERIAL_8250_NR_UARTS=4
CONFIG_SERIAL_8250_RUNTIME_UARTS=4
CONFIG_SERIAL_CORE=y
CONFIG_UNIX98_PTYS=y
CONFIG_PRINTER=m
CONFIG_RTC=y
CONFIG_DEVPORT=y
CONFIG_I2C=y
CONFIG_I2C_BOARDINFO=y
CONFIG_I2C_CHARDEV=y
CONFIG_I2C_VIAPRO=y
CONFIG_HWMON=y
CONFIG_HWMON_VID=y
CONFIG_SENSORS_W83627HF=y
CONFIG_SSB_POSSIBLE=y
CONFIG_VIDEO_DEV=y
CONFIG_VIDEO_V4L2=y
CONFIG_VIDEO_CAPTURE_DRIVERS=y
CONFIG_VIDEO_HELPER_CHIPS_AUTO=y
CONFIG_V4L_USB_DRIVERS=y
CONFIG_USB_SN9C102=y
CONFIG_AGP=y
CONFIG_AGP_VIA=y
CONFIG_DRM=m
CONFIG_DRM_RADEON=m
CONFIG_VGA_CONSOLE=y
CONFIG_VIDEO_SELECT=y
CONFIG_DUMMY_CONSOLE=y
CONFIG_SOUND=y
CONFIG_SND=y
CONFIG_SND_TIMER=y
CONFIG_SND_PCM=y
CONFIG_SND_HWDEP=y
CONFIG_SND_RAWMIDI=y
CONFIG_SND_SEQUENCER=y
CONFIG_SND_SEQ_DUMMY=m
CONFIG_SND_OSSEMUL=y
CONFIG_SND_MIXER_OSS=y
CONFIG_SND_PCM_OSS=y
CONFIG_SND_PCM_OSS_PLUGINS=y
CONFIG_SND_SEQUENCER_OSS=y
CONFIG_SND_RTCTIMER=y
CONFIG_SND_SEQ_RTCTIMER_DEFAULT=y
CONFIG_SND_SUPPORT_OLD_API=y
CONFIG_SND_VERBOSE_PROCFS=y
CONFIG_SND_MPU401_UART=m
CONFIG_SND_AC97_CODEC=y
CONFIG_SND_MPU401=m
CONFIG_SND_EMU10K1=y
CONFIG_SND_INTEL8X0=y
CONFIG_AC97_BUS=y
CONFIG_HID_SUPPORT=y
CONFIG_USB_SUPPORT=y
CONFIG_USB_ARCH_HAS_HCD=y
CONFIG_USB_ARCH_HAS_OHCI=y
CONFIG_USB_ARCH_HAS_EHCI=y
CONFIG_USB=y
CONFIG_USB_DEVICEFS=y
CONFIG_USB_DYNAMIC_MINORS=y
CONFIG_USB_UHCI_HCD=y
CONFIG_USB_PRINTER=y
CONFIG_USB_STORAGE=m
CONFIG_AUXDISPLAY=y
CONFIG_DMIID=y
CONFIG_EXT2_FS=y
CONFIG_EXT2_FS_XATTR=y
CONFIG_EXT2_FS_POSIX_ACL=y
CONFIG_EXT3_FS=y
CONFIG_EXT3_FS_XATTR=y
CONFIG_EXT3_FS_POSIX_ACL=y
CONFIG_JBD=y
CONFIG_FS_MBCACHE=y
CONFIG_REISERFS_FS=y
CONFIG_REISERFS_FS_XATTR=y
CONFIG_REISERFS_FS_POSIX_ACL=y
CONFIG_FS_POSIX_ACL=y
CONFIG_INOTIFY=y
CONFIG_INOTIFY_USER=y
CONFIG_QUOTA=y
CONFIG_QUOTA_NETLINK_INTERFACE=y
CONFIG_PRINT_QUOTA_WARNING=y
CONFIG_QFMT_V2=y
CONFIG_QUOTACTL=y
CONFIG_DNOTIFY=y
CONFIG_FUSE_FS=y
CONFIG_GENERIC_ACL=y
CONFIG_ISO9660_FS=y
CONFIG_JOLIET=y
CONFIG_ZISOFS=y
CONFIG_UDF_FS=y
CONFIG_UDF_NLS=y
CONFIG_FAT_FS=y
CONFIG_MSDOS_FS=y
CONFIG_VFAT_FS=m
CONFIG_FAT_DEFAULT_CODEPAGE=437
CONFIG_FAT_DEFAULT_IOCHARSET="iso8859-1"
CONFIG_PROC_FS=y
CONFIG_PROC_SYSCTL=y
CONFIG_SYSFS=y
CONFIG_TMPFS=y
CONFIG_TMPFS_POSIX_ACL=y
CONFIG_HUGETLBFS=y
CONFIG_HUGETLB_PAGE=y
CONFIG_CONFIGFS_FS=y
CONFIG_NETWORK_FILESYSTEMS=y
CONFIG_NFS_FS=y
CONFIG_NFS_V3=y
CONFIG_NFS_V3_ACL=y
CONFIG_NFSD=y
CONFIG_NFSD_V2_ACL=y
CONFIG_NFSD_V3=y
CONFIG_NFSD_V3_ACL=y
CONFIG_NFSD_TCP=y
CONFIG_LOCKD=y
CONFIG_LOCKD_V4=y
CONFIG_EXPORTFS=y
CONFIG_NFS_ACL_SUPPORT=y
CONFIG_NFS_COMMON=y
CONFIG_SUNRPC=y
CONFIG_PARTITION_ADVANCED=y
CONFIG_MSDOS_PARTITION=y
CONFIG_NLS=y
CONFIG_NLS_DEFAULT="iso8859-1"
CONFIG_NLS_CODEPAGE_437=y
CONFIG_NLS_ASCII=m
CONFIG_NLS_ISO8859_1=y
CONFIG_NLS_ISO8859_15=m
CONFIG_NLS_UTF8=m
CONFIG_INSTRUMENTATION=y
CONFIG_PROFILING=y
CONFIG_OPROFILE=y
CONFIG_KPROBES=y
CONFIG_MARKERS=y
CONFIG_TRACE_IRQFLAGS_SUPPORT=y
CONFIG_ENABLE_WARN_DEPRECATED=y
CONFIG_ENABLE_MUST_CHECK=y
CONFIG_DEBUG_FS=y
CONFIG_DEBUG_KERNEL=y
CONFIG_DETECT_SOFTLOCKUP=y
CONFIG_SCHEDSTATS=y
CONFIG_TIMER_STATS=y
CONFIG_DEBUG_BUGVERBOSE=y
CONFIG_EARLY_PRINTK=y
CONFIG_DEBUG_STACKOVERFLOW=y
CONFIG_4KSTACKS=y
CONFIG_X86_FIND_SMP_CONFIG=y
CONFIG_X86_MPPARSE=y
CONFIG_DOUBLEFAULT=y
CONFIG_SECURITY_FILE_CAPABILITIES=y
CONFIG_CRYPTO=y
CONFIG_CRYPTO_ALGAPI=y
CONFIG_CRYPTO_BLKCIPHER=y
CONFIG_CRYPTO_MANAGER=y
CONFIG_CRYPTO_CBC=y
CONFIG_BITREVERSE=y
CONFIG_CRC32=y
CONFIG_ZLIB_INFLATE=y
CONFIG_PLIST=y
CONFIG_HAS_IOMEM=y
CONFIG_HAS_IOPORT=y
CONFIG_HAS_DMA=y

Re: 2.6.24.2: 4KSTACKS + pcdrw + dm + mount -> stack overflow: ide-cd related? dm-related?

[Nix]

On 24 Feb 2008, nix@esperi.org.uk outgrape:

> A loop mount/umounting a pcdrw or iso9660 (through the pktcdvd device)
> sees a stack overflow in four or five tries. Doing the same thing with
> the same CD in a normal non-pktcdvd-mounted drive doesn't cause a crash.

> (This may or may not be PREEMPT+PREEMPT_BKL-specific: I'll try turning
> them off tomorrow and repeating.)

It is not preempt-specific, nor dm-specific. Nor it is very easy to
capture tracebacks of: even netconsole generally gives up when faced
with a string of recursive tracebacks blurring past forever at blinding
speed.

But while I'd normally blame pktcdvd there's only one pktcdvd function
in these tracebacks (pkt_open) and it's not got a significant stack
footprint.

More notable is a great stack of mutual recursion between
dm_bio_destructor() and the CDROM code: it seems to burn most of the
stack on this sort of thrashing. Here's one of those tracebacks again:

do_IRQ: stack overflow: 480
id: 4645, comm: mount Not tainted 2.6.24.2-dirty #4
 [<c0104171>] do_IRQ+0x66/0xc5
 [<c0102f8b>] common_interrupt+0x23/0x28
 [<c027b5da>] ide_outsl+0x5/0x9
 [<c027c540>] ata_output_data+0x4d/0x64
 [<c027b8a6>] atapi_output_bytes+0x19/0x3f
 [<c0285377>] cdrom_transfer_packet_command+0xb5/0xde
 [<c0282607>] cdrom_timer_expiry+0x0/0x51
 [<c02840c3>] cdrom_start_packet_command+0x14f/0x157
 [<c02853e9>] cdrom_do_pc_continuation+0x0/0x2c
 [<c027aa33>] ide_do_request+0x70a/0x943
 [<c0363ef3>] schedule_timeout+0x13/0x8b
 [<c021faeb>] elv_drain_elevator+0x15/0x58
 [<c0220277>] elv_insert+0xf6/0x1d9
 [<c0285377>] cdrom_transfer_packet_command+0xb5/0xde
 [<c0282607>] cdrom_timer_expiry+0x0/0x51
 [<c027b038>] ide_do_drive_cmd+0x99/0xe9
 [<c0282abe>] cdrom_queue_packet_command+0x35/0xa9
 [<c0363b2b>] schedule+0x321/0x33e
 [<c0363ef3>] schedule_timeout+0x13/0x8b
 [<c0282d11>] cdrom_read_tocentry+0x96/0xa1
 [<c02220d3>] blk_end_sync_rq+0x0/0x23
 [<c028315b>] cdrom_read_toc+0x14b/0x42e
 [<c02220d3>] blk_end_sync_rq+0x0/0x23
 [<c027b07e>] ide_do_drive_cmd+0xdf/0xe9
 [<c0283ed2>] ide_cdrom_audio_ioctl+0x13c/0x1de
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0282f42>] cdrom_check_status+0x55/0x60
 [<c02220d3>] blk_end_sync_rq+0x0/0x23
 [<c02865ba>] cdrom_count_tracks+0x64/0x16a
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c02896c4>] cdrom_open+0x190/0x8f8
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c02252d3>] get_disk+0x4e/0x65
 [<c02252f1>] exact_lock+0x7/0xd
 [<c025a2cc>] kobj_lookup+0x104/0x12e
 [<c02828e8>] idecd_open+0x72/0x86
 [<c0174458>] do_open+0x198/0x238
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c0174561>] __blkdev_get+0x69/0x74
 [<c017457e>] blkdev_get+0x12/0x14
 [<c0263333>] pkt_open+0x8d/0xc96
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c017162c>] end_bio_bh_io_sync+0x0/0x27
 [<c0172e9a>] bio_fs_destructor+0x0/0xb
 [<c02afbd9>] clone_endio+0x0/0xa3
 [<c02af8fe>] dm_bio_destructor+0x0/0x8
 [<c022998c>] kobject_get+0xf/0x13
 [<c02252d3>] get_disk+0x4e/0x65
 [<c02252f1>] exact_lock+0x7/0xd
 [<c025a2cc>] kobj_lookup+0x104/0x12e
 [<c0224ed0>] exact_match+0x0/0x4
 [<c0174344>] do_open+0x84/0x238
 [<c0174561>] 
EIP: 0060:[<c01033d2>] EFLAGS: 00010093 CPU: 0
EIP is at dump_trace+0x52/0x8b
EAX: 0000082a EBX: 00000046 ECX: 0000020a EDX: 00000000
ESI: 00000000 EDI: 00000000 EBP: 00000ffc ESP: eeede1c4
 DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068
rocess mount (pid: 4645, ti=eeede000 task=ee537320 task.ti=eeede000)v<tack:  00001000 c03f6c0c 00000000 c0523b64 00000000 c0103423 c036e79c c03f6c0c 
       00000002 c0103bf2 c03f6c0c c0103f85 c03ccd19 00001225 ee5375d0 c0505178 
       c0429436 00000002 c0429477 eeede220 0000000d c0104171 c03cce23 000001e0 

Just looking for `dm_' in there should point out something odd.  (Of
course dm is just acting on behalf of others here, so it may be that the
IDE CDROM code is doing something demented: in which case why does this
only stack-overrun if I mount /dev/pktcdvd/cdrw, and not /dev/cdrw?
For that matter, why is dm getting involved at all? This CD-RW isn't
dm-managed in any way, shape or form...)

-- 
`The rest is a tale of post and counter-post.' --- Ian Rawlings
                                                   describes USENET

Re: 2.6.24.2: 4KSTACKS + pcdrw + dm + mount -> stack overflow: ide-cd related? dm-related?

[Peter Osterlund]

Nix <nix@esperi.org.uk> writes:

> On 24 Feb 2008, nix@esperi.org.uk outgrape:
>
>> A loop mount/umounting a pcdrw or iso9660 (through the pktcdvd device)
>> sees a stack overflow in four or five tries. Doing the same thing with
>> the same CD in a normal non-pktcdvd-mounted drive doesn't cause a crash.
>
>> (This may or may not be PREEMPT+PREEMPT_BKL-specific: I'll try turning
>> them off tomorrow and repeating.)
>
> It is not preempt-specific, nor dm-specific. Nor it is very easy to
> capture tracebacks of: even netconsole generally gives up when faced
> with a string of recursive tracebacks blurring past forever at blinding
> speed.
>
> But while I'd normally blame pktcdvd there's only one pktcdvd function
> in these tracebacks (pkt_open) and it's not got a significant stack
> footprint.

Did you verify that with "make checkstack" or just by looking at the
source code? On my system, pkt_open() consumes 584 bytes because the
compiler decides to inline lots of functions that would not normally
be part of long call chains. The following patch fixes that problem on
my system.

> More notable is a great stack of mutual recursion between
> dm_bio_destructor() and the CDROM code: it seems to burn most of the
> stack on this sort of thrashing. Here's one of those tracebacks again:

Maybe dm_bio_destructor() is just old cruft left on the stack from
previous function calls?


From: Peter Osterlund <petero2@telia.com>

Signed-off-by: Peter Osterlund <petero2@telia.com>
---

 drivers/block/pktcdvd.c |   16 ++++++++--------
 1 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
index 674cd66..f2510e7 100644
--- a/drivers/block/pktcdvd.c
+++ b/drivers/block/pktcdvd.c
@@ -849,7 +849,7 @@ static int pkt_flush_cache(struct pktcdvd_device *pd)
 /*
  * speed is given as the normal factor, e.g. 4 for 4x
  */
-static int pkt_set_speed(struct pktcdvd_device *pd, unsigned write_speed, unsigned read_speed)
+static noinline int pkt_set_speed(struct pktcdvd_device *pd, unsigned write_speed, unsigned read_speed)
 {
 	struct packet_command cgc;
 	struct request_sense sense;
@@ -1776,7 +1776,7 @@ static int pkt_get_track_info(struct pktcdvd_device *pd, __u16 track, __u8 type,
 	return pkt_generic_packet(pd, &cgc);
 }
 
-static int pkt_get_last_written(struct pktcdvd_device *pd, long *last_written)
+static noinline int pkt_get_last_written(struct pktcdvd_device *pd, long *last_written)
 {
 	disc_information di;
 	track_information ti;
@@ -1813,7 +1813,7 @@ static int pkt_get_last_written(struct pktcdvd_device *pd, long *last_written)
 /*
  * write mode select package based on pd->settings
  */
-static int pkt_set_write_settings(struct pktcdvd_device *pd)
+static noinline int pkt_set_write_settings(struct pktcdvd_device *pd)
 {
 	struct packet_command cgc;
 	struct request_sense sense;
@@ -1972,7 +1972,7 @@ static int pkt_writable_disc(struct pktcdvd_device *pd, disc_information *di)
 	return 1;
 }
 
-static int pkt_probe_settings(struct pktcdvd_device *pd)
+static noinline int pkt_probe_settings(struct pktcdvd_device *pd)
 {
 	struct packet_command cgc;
 	unsigned char buf[12];
@@ -2071,7 +2071,7 @@ static int pkt_probe_settings(struct pktcdvd_device *pd)
 /*
  * enable/disable write caching on drive
  */
-static int pkt_write_caching(struct pktcdvd_device *pd, int set)
+static noinline int pkt_write_caching(struct pktcdvd_device *pd, int set)
 {
 	struct packet_command cgc;
 	struct request_sense sense;
@@ -2116,7 +2116,7 @@ static int pkt_lock_door(struct pktcdvd_device *pd, int lockflag)
 /*
  * Returns drive maximum write speed
  */
-static int pkt_get_max_speed(struct pktcdvd_device *pd, unsigned *write_speed)
+static noinline int pkt_get_max_speed(struct pktcdvd_device *pd, unsigned *write_speed)
 {
 	struct packet_command cgc;
 	struct request_sense sense;
@@ -2177,7 +2177,7 @@ static char us_clv_to_speed[16] = {
 /*
  * reads the maximum media speed from ATIP
  */
-static int pkt_media_speed(struct pktcdvd_device *pd, unsigned *speed)
+static noinline int pkt_media_speed(struct pktcdvd_device *pd, unsigned *speed)
 {
 	struct packet_command cgc;
 	struct request_sense sense;
@@ -2249,7 +2249,7 @@ static int pkt_media_speed(struct pktcdvd_device *pd, unsigned *speed)
 	}
 }
 
-static int pkt_perform_opc(struct pktcdvd_device *pd)
+static noinline int pkt_perform_opc(struct pktcdvd_device *pd)
 {
 	struct packet_command cgc;
 	struct request_sense sense;

-- 
Peter Osterlund - petero2@telia.com
http://web.telia.com/~u89404340

Re: 2.6.24.2: 4KSTACKS + pcdrw + dm + mount -> stack overflow: ide-cd related? dm-related?

[Nix]

On 24 Feb 2008, Peter Osterlund told this:

> Nix <nix@esperi.org.uk> writes:
>> But while I'd normally blame pktcdvd there's only one pktcdvd function
>> in these tracebacks (pkt_open) and it's not got a significant stack
>> footprint.
>
> Did you verify that with "make checkstack" or just by looking at the
> source code? On my system, pkt_open() consumes 584 bytes because the
> compiler decides to inline lots of functions that would not normally
> be part of long call chains. The following patch fixes that problem on
> my system.

I just looked at the source; I forgot `make checkstack' existed.

On this system:

0xc0263e0f pkt_open [vmlinux]:                          556

which is nearly as bad.

(As an aside, I'm surprised I didn't oops when packet-writing as well:

0xc021270d udf_process_sequence [vmlinux]:              692
0xc020f43d udf_add_entry [vmlinux]:                     628

owch. I guess that's called via a shorter call chain...)


I'll try the patch after this series of backups is done :)

-- 
`The rest is a tale of post and counter-post.' --- Ian Rawlings
                                                   describes USENET

Re: 2.6.24.2: 4KSTACKS + pcdrw + dm + mount -> stack overflow: ide-cd related? dm-related?

[Andrew Morton]

On Sun, 24 Feb 2008 17:02:26 +0000 Nix <nix@esperi.org.uk> wrote:

> On 24 Feb 2008, Peter Osterlund told this:
> 
> > Nix <nix@esperi.org.uk> writes:
> >> But while I'd normally blame pktcdvd there's only one pktcdvd function
> >> in these tracebacks (pkt_open) and it's not got a significant stack
> >> footprint.
> >
> > Did you verify that with "make checkstack" or just by looking at the
> > source code? On my system, pkt_open() consumes 584 bytes because the
> > compiler decides to inline lots of functions that would not normally
> > be part of long call chains. The following patch fixes that problem on
> > my system.
> 
> I just looked at the source; I forgot `make checkstack' existed.
> 
> On this system:
> 
> 0xc0263e0f pkt_open [vmlinux]:                          556
> 
> which is nearly as bad.
> 
> (As an aside, I'm surprised I didn't oops when packet-writing as well:
> 
> 0xc021270d udf_process_sequence [vmlinux]:              692
> 0xc020f43d udf_add_entry [vmlinux]:                     628
> 
> owch. I guess that's called via a shorter call chain...)

udf_process_sequence() seems to be another victim of gcc inlining.

udf_add_entry() defines a couple of 256-byte local arrays.

Re: 2.6.24.2: 4KSTACKS + pcdrw + dm + mount -> stack overflow: ide-cd related? dm-related?

[Jan Kara]

> On Sun, 24 Feb 2008 17:02:26 +0000 Nix <nix@esperi.org.uk> wrote:
> 
> > On 24 Feb 2008, Peter Osterlund told this:
> > 
> > > Nix <nix@esperi.org.uk> writes:
> > >> But while I'd normally blame pktcdvd there's only one pktcdvd function
> > >> in these tracebacks (pkt_open) and it's not got a significant stack
> > >> footprint.
> > >
> > > Did you verify that with "make checkstack" or just by looking at the
> > > source code? On my system, pkt_open() consumes 584 bytes because the
> > > compiler decides to inline lots of functions that would not normally
> > > be part of long call chains. The following patch fixes that problem on
> > > my system.
> > 
> > I just looked at the source; I forgot `make checkstack' existed.
> > 
> > On this system:
> > 
> > 0xc0263e0f pkt_open [vmlinux]:                          556
> > 
> > which is nearly as bad.
> > 
> > (As an aside, I'm surprised I didn't oops when packet-writing as well:
> > 
> > 0xc021270d udf_process_sequence [vmlinux]:              692
> > 0xc020f43d udf_add_entry [vmlinux]:                     628
> > 
> > owch. I guess that's called via a shorter call chain...)
> 
> udf_process_sequence() seems to be another victim of gcc inlining.
  Hmm, I'll have a look what we can do.

> udf_add_entry() defines a couple of 256-byte local arrays.
  Yes, exactly two of them. One is  non-trivial to get rid of - it's
used for encoding of filename before we write it, but one is used during
scanning of the directory whether the entry doesn't already exists (oh,
my!) and we can just rip that off..

								Honza
-- 
Jan Kara <jack@suse.cz>
SuSE CR Labs

Re: 2.6.24.2: 4KSTACKS + pcdrw + dm + mount -> stack overflow: ide-cd related? dm-related?

[Andrew Morton]

On Mon, 25 Feb 2008 23:48:07 +0100 Jan Kara <jack@suse.cz> wrote:

> > udf_process_sequence() seems to be another victim of gcc inlining.
>   Hmm, I'll have a look what we can do.

noinline...

> > udf_add_entry() defines a couple of 256-byte local arrays.
>   Yes, exactly two of them. One is  non-trivial to get rid of - it's
> used for encoding of filename before we write it, but one is used during
> scanning of the directory whether the entry doesn't already exists (oh,
> my!) and we can just rip that off..

kmalloc is quite fast ;)

Re: 2.6.24.2: 4KSTACKS + pcdrw + dm + mount -> stack overflow: ide-cd related? dm-related?

[Jiri Kosina]

On Mon, 25 Feb 2008, Jan Kara wrote:

>   Yes, exactly two of them. One is  non-trivial to get rid of - it's
> used for encoding of filename before we write it, 

Why can't we do just



UDF: Optimize stack usage

Signed-off-by: Jiri Kosina <jkosina@suse.cz>

diff --git a/fs/udf/namei.c b/fs/udf/namei.c
index 112a5fb..706a2b5 100644
--- a/fs/udf/namei.c
+++ b/fs/udf/namei.c
@@ -336,7 +336,7 @@ static struct fileIdentDesc *udf_add_entry(struct inode *dir,
 {
 	struct super_block *sb = dir->i_sb;
 	struct fileIdentDesc *fi = NULL;
-	char name[UDF_NAME_LEN], fname[UDF_NAME_LEN];
+	char *name, *fname;
 	int namelen;
 	loff_t f_pos;
 	int flen;
@@ -352,6 +352,14 @@ static struct fileIdentDesc *udf_add_entry(struct inode *dir,
 	struct extent_position epos = {};
 	struct udf_inode_info *dinfo;
 
+	name = kmalloc(sizeof(char) * UDF_NAME_LEN, GFP_KERNEL);
+	fname = kmalloc(sizeof(char) * UDF_NAME_LEN, GFP_KERNEL);
+
+	if (!name || !fname) {
+		*err = -ENOMEM;
+		return NULL;
+	}
+
 	if (dentry) {
 		if (!dentry->d_name.len) {
 			*err = -EINVAL;
diff --git a/fs/udf/super.c b/fs/udf/super.c
index f3ac4ab..42e3ba8 100644
--- a/fs/udf/super.c
+++ b/fs/udf/super.c
@@ -1345,7 +1345,7 @@ static void udf_load_logicalvolint(struct super_block *sb, kernel_extent_ad loc)
  *	July 1, 1997 - Andrew E. Mileski
  *	Written, tested, and released.
  */
-static int udf_process_sequence(struct super_block *sb, long block,
+static int noinline udf_process_sequence(struct super_block *sb, long block,
 				long lastblock, kernel_lb_addr *fileset)
 {
 	struct buffer_head *bh = NULL;

Re: 2.6.24.2: 4KSTACKS + pcdrw + dm + mount -> stack overflow: ide-cd related? dm-related?

[Ingo Molnar]

* Jiri Kosina <jkosina@suse.cz> wrote:

> +	name = kmalloc(sizeof(char) * UDF_NAME_LEN, GFP_KERNEL);
> +	fname = kmalloc(sizeof(char) * UDF_NAME_LEN, GFP_KERNEL);
> +
> +	if (!name || !fname) {
> +		*err = -ENOMEM;
> +		return NULL;
> +	}
> +
>  	if (dentry) {
>  		if (!dentry->d_name.len) {
>  			*err = -EINVAL;

this bit is missing i think:

	if (name)
		kfree(name);
	if (fname)
		kfree(fname);

	Ingo

Re: 2.6.24.2: 4KSTACKS + pcdrw + dm + mount -> stack overflow: ide-cd related? dm-related?

[Jiri Kosina]

On Tue, 26 Feb 2008, Ingo Molnar wrote:

> > +	name = kmalloc(sizeof(char) * UDF_NAME_LEN, GFP_KERNEL);
> > +	fname = kmalloc(sizeof(char) * UDF_NAME_LEN, GFP_KERNEL);
> > +
> > +	if (!name || !fname) {
> > +		*err = -ENOMEM;
> > +		return NULL;
> > +	}
> > +
> >  	if (dentry) {
> >  		if (!dentry->d_name.len) {
> >  			*err = -EINVAL;
> this bit is missing i think:
> 	if (name)
> 		kfree(name);
> 	if (fname)
> 		kfree(fname);

Ergh, of course, stupid me, sorry, it should be freed on all exit paths. I 
am not sending updated patch, as Jan is probably working on complete 
removal of one of those fields ... ?

Thanks,

-- 
Jiri Kosina

Re: 2.6.24.2: 4KSTACKS + pcdrw + dm + mount -> stack overflow: ide-cd related? dm-related?

[Jan Kara]

On Tue 26-02-08 12:37:17, Jiri Kosina wrote:
> On Tue, 26 Feb 2008, Ingo Molnar wrote:
> 
> > > +	name = kmalloc(sizeof(char) * UDF_NAME_LEN, GFP_KERNEL);
> > > +	fname = kmalloc(sizeof(char) * UDF_NAME_LEN, GFP_KERNEL);
> > > +
> > > +	if (!name || !fname) {
> > > +		*err = -ENOMEM;
> > > +		return NULL;
> > > +	}
> > > +
> > >  	if (dentry) {
> > >  		if (!dentry->d_name.len) {
> > >  			*err = -EINVAL;
> > this bit is missing i think:
> > 	if (name)
> > 		kfree(name);
> > 	if (fname)
> > 		kfree(fname);
> 
> Ergh, of course, stupid me, sorry, it should be freed on all exit paths. I 
> am not sending updated patch, as Jan is probably working on complete 
> removal of one of those fields ... ?
  Yes, I'll convert one variable to kmalloc and the other one remove
completely. Stay tuned ;).

								Honza
-- 
Jan Kara <jack@suse.cz>
SUSE Labs, CR

Re: 2.6.24.2: 4KSTACKS + pcdrw + dm + mount -> stack overflow: ide-cd related? dm-related?

[Daniel Hazelton]

On Tuesday 26 February 2008 06:10:34 Jiri Kosina wrote:
> On Mon, 25 Feb 2008, Jan Kara wrote:
> >   Yes, exactly two of them. One is  non-trivial to get rid of - it's
> > used for encoding of filename before we write it,
>
> Why can't we do just
>
>
>
> UDF: Optimize stack usage
>
> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
>
> diff --git a/fs/udf/namei.c b/fs/udf/namei.c
> index 112a5fb..706a2b5 100644
> --- a/fs/udf/namei.c
> +++ b/fs/udf/namei.c
> @@ -336,7 +336,7 @@ static struct fileIdentDesc *udf_add_entry(struct inode
> *dir, {
>  	struct super_block *sb = dir->i_sb;
>  	struct fileIdentDesc *fi = NULL;
> -	char name[UDF_NAME_LEN], fname[UDF_NAME_LEN];
> +	char *name, *fname;
>  	int namelen;
>  	loff_t f_pos;
>  	int flen;
> @@ -352,6 +352,14 @@ static struct fileIdentDesc *udf_add_entry(struct
> inode *dir, struct extent_position epos = {};
>  	struct udf_inode_info *dinfo;
>
> +	name = kmalloc(sizeof(char) * UDF_NAME_LEN, GFP_KERNEL);
> +	fname = kmalloc(sizeof(char) * UDF_NAME_LEN, GFP_KERNEL);
> +
> +	if (!name || !fname) {
> +		*err = -ENOMEM;
> +		return NULL;
> +	}
> +

Wouldn't it be better to check each individually, so you do wind up leaking a 
buffer here if one gets allocated and the other doesn't ?

>  	if (dentry) {
>  		if (!dentry->d_name.len) {
>  			*err = -EINVAL;
> diff --git a/fs/udf/super.c b/fs/udf/super.c
> index f3ac4ab..42e3ba8 100644
> --- a/fs/udf/super.c
> +++ b/fs/udf/super.c
> @@ -1345,7 +1345,7 @@ static void udf_load_logicalvolint(struct super_block
> *sb, kernel_extent_ad loc) *	July 1, 1997 - Andrew E. Mileski
>   *	Written, tested, and released.
>   */
> -static int udf_process_sequence(struct super_block *sb, long block,
> +static int noinline udf_process_sequence(struct super_block *sb, long
> block, long lastblock, kernel_lb_addr *fileset)
>  {
>  	struct buffer_head *bh = NULL;
> --
> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/

DRH

-- 
Dialup is like pissing through a pipette. Slow and excruciatingly painful.

Re: 2.6.24.2: 4KSTACKS + pcdrw + dm + mount -> stack overflow: ide-cd related? dm-related?

[Jan Kara]

> On 24 Feb 2008, Peter Osterlund told this:
> 
> > Nix <nix@esperi.org.uk> writes:
> >> But while I'd normally blame pktcdvd there's only one pktcdvd function
> >> in these tracebacks (pkt_open) and it's not got a significant stack
> >> footprint.
> >
> > Did you verify that with "make checkstack" or just by looking at the
> > source code? On my system, pkt_open() consumes 584 bytes because the
> > compiler decides to inline lots of functions that would not normally
> > be part of long call chains. The following patch fixes that problem on
> > my system.
> 
> I just looked at the source; I forgot `make checkstack' existed.
> 
> On this system:
> 
> 0xc0263e0f pkt_open [vmlinux]:                          556
> 
> which is nearly as bad.
> 
> (As an aside, I'm surprised I didn't oops when packet-writing as well:
> 
> 0xc021270d udf_process_sequence [vmlinux]:              692
> 0xc020f43d udf_add_entry [vmlinux]:                     628
> 
> owch. I guess that's called via a shorter call chain...)
> 
> 
> I'll try the patch after this series of backups is done :)
  If you are interested, linux-next or -mm tree should contain a patch now
that fixes the problem...

								Honza
-- 
Jan Kara <jack@suse.cz>
SuSE CR Labs

Re: 2.6.24.2: 4KSTACKS + pcdrw + dm + mount -> stack overflow: ide-cd related? dm-related?

[Nix]

On 6 Mar 2008, Jan Kara said:
>   If you are interested, linux-next or -mm tree should contain a patch now
> that fixes the problem...

As soon as I've figured out why dhclient is failing to establish DHCP
connections from 2.6.14.3 (the DHCPOFFERs seem to get ignored, it's
weird and the kernel shouldn't have anything to do with it, but it does)
so I can actually compile something that works and doesn't knock me off
the net every two minutes, I'll try it :)

(yes, I could try -mm directly, but it's been some weeks since I backed
up, thanks to an abruptly chocolate-filled CD-RW drive, so I'm being a
bit cautious.)

-- 
`The rest is a tale of post and counter-post.' --- Ian Rawlings
                                                   describes USENET

Re: 2.6.24.2: 4KSTACKS + pcdrw + dm + mount -> stack overflow: ide-cd related? dm-related?

[Andrew Morton]

On Sun, 24 Feb 2008 17:56:09 +0100 Peter Osterlund <petero2@telia.com> wrote:

> 
>  drivers/block/pktcdvd.c |   16 ++++++++--------
>  1 files changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/block/pktcdvd.c b/drivers/block/pktcdvd.c
> index 674cd66..f2510e7 100644
> --- a/drivers/block/pktcdvd.c
> +++ b/drivers/block/pktcdvd.c
> @@ -849,7 +849,7 @@ static int pkt_flush_cache(struct pktcdvd_device *pd)
>  /*
>   * speed is given as the normal factor, e.g. 4 for 4x
>   */
> -static int pkt_set_speed(struct pktcdvd_device *pd, unsigned write_speed, unsigned read_speed)
> +static noinline int pkt_set_speed(struct pktcdvd_device *pd, unsigned write_speed, unsigned read_speed)
>
> ...

yup, I'll grab that.  I'll even write your changelog for you (grr).

But first, let's do this:


From: Andrew Morton <akpm@linux-foundation.org>

People are adding `noinline' in various places to prevent excess stack
consumption due to gcc inlining.  But once this is done, it is quite unobvious
why the `noinline' is present in the code.  We can comment each and every
site, or we can use noinline_for_stack.


Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 include/linux/compiler.h |    6 ++++++
 1 file changed, 6 insertions(+)

diff -puN include/linux/compiler.h~add-noinline_for_stack include/linux/compiler.h
--- a/include/linux/compiler.h~add-noinline_for_stack
+++ a/include/linux/compiler.h
@@ -138,6 +138,12 @@ extern void __chk_io_ptr(const volatile 
 #define noinline
 #endif
 
+/*
+ * Rather then using noinline to prevent stack consumption, use
+ * noinline_for_stack instead.  For documentaiton reasons.
+ */
+#define noinline_for_stack noinline
+
 #ifndef __always_inline
 #define __always_inline inline
 #endif
_

(Note that these changes don't let DM off the hook!)