reiserfs locking (v2)

From: Sergey Senozhatsky
Date: Fri Jul 02 2010 - 05:30:53 EST

Hello,

I searched lkml and found the following report (titled reiserfs locking):
http://lkml.org/lkml/2010/4/15/389 (Fri, 16 Apr 2010)

I can see this backtrace while configuring emacs:

[ 6136.579013]
[ 6136.579015] =======================================================
[ 6136.579021] [ INFO: possible circular locking dependency detected ]
[ 6136.579025] 2.6.35-rc3-dbg-git3-00350-g94d119f #61
[ 6136.579027] -------------------------------------------------------
[ 6136.579031] conftest/13950 is trying to acquire lock:
[ 6136.579034] (&sb->s_type->i_mutex_key#10){+.+.+.}, at: [<c10f1cf6>] reiserfs_file_release+0x11d/0x344
[ 6136.579050]
[ 6136.579051] but task is already holding lock:
[ 6136.579054] (&mm->mmap_sem){++++++}, at: [<c1091b87>] sys_munmap+0x26/0x42
[ 6136.579064]
[ 6136.579065] which lock already depends on the new lock.
[ 6136.579066]
[ 6136.579069]
[ 6136.579070] the existing dependency chain (in reverse order) is:
[ 6136.579073]
[ 6136.579074] -> #1 (&mm->mmap_sem){++++++}:
[ 6136.579081] [<c104f53a>] lock_acquire+0x59/0x70
[ 6136.579089] [<c108cf78>] might_fault+0x53/0x70
[ 6136.579094] [<c11853b8>] copy_to_user+0x30/0x48
[ 6136.579101] [<c10afaf9>] filldir64+0x95/0xc9
[ 6136.579106] [<c10f2504>] reiserfs_readdir_dentry+0x35d/0x4d9
[ 6136.579112] [<c10f2692>] reiserfs_readdir+0x12/0x17
[ 6136.579117] [<c10afd17>] vfs_readdir+0x6d/0x92
[ 6136.579122] [<c10afe91>] sys_getdents64+0x63/0xa2
[ 6136.579127] [<c10027d3>] sysenter_do_call+0x12/0x32
[ 6136.579134]
[ 6136.579135] -> #0 (&sb->s_type->i_mutex_key#10){+.+.+.}:
[ 6136.579142] [<c104ef30>] __lock_acquire+0x96d/0xbe1
[ 6136.579148] [<c104f53a>] lock_acquire+0x59/0x70
[ 6136.579153] [<c12c5614>] __mutex_lock_common+0x39/0x36b
[ 6136.579160] [<c12c5980>] mutex_lock_nested+0x12/0x15
[ 6136.579165] [<c10f1cf6>] reiserfs_file_release+0x11d/0x344
[ 6136.579171] [<c10a580d>] fput+0xe0/0x16a
[ 6136.579177] [<c1090ca6>] remove_vma+0x28/0x47
[ 6136.579182] [<c1091a68>] do_munmap+0x1e8/0x200
[ 6136.579188] [<c1091b93>] sys_munmap+0x32/0x42
[ 6136.579193] [<c10027d3>] sysenter_do_call+0x12/0x32
[ 6136.579198]
[ 6136.579199] other info that might help us debug this:
[ 6136.579200]
[ 6136.579204] 1 lock held by conftest/13950:
[ 6136.579207] #0: (&mm->mmap_sem){++++++}, at: [<c1091b87>] sys_munmap+0x26/0x42
[ 6136.579216]
[ 6136.579217] stack backtrace:
[ 6136.579221] Pid: 13950, comm: conftest Not tainted 2.6.35-rc3-dbg-git3-00350-g94d119f #61
[ 6136.579225] Call Trace:
[ 6136.579230] [<c12c4893>] ? printk+0xf/0x11
[ 6136.579235] [<c104dbdd>] print_circular_bug+0x8a/0x96
[ 6136.579241] [<c104ef30>] __lock_acquire+0x96d/0xbe1
[ 6136.579247] [<c104e436>] ? mark_lock+0x26/0x1b3
[ 6136.579254] [<c104f53a>] lock_acquire+0x59/0x70
[ 6136.579259] [<c10f1cf6>] ? reiserfs_file_release+0x11d/0x344
[ 6136.579265] [<c12c5614>] __mutex_lock_common+0x39/0x36b
[ 6136.579270] [<c10f1cf6>] ? reiserfs_file_release+0x11d/0x344
[ 6136.579276] [<c1084375>] ? release_pages+0x55/0x116
[ 6136.579282] [<c12c5980>] mutex_lock_nested+0x12/0x15
[ 6136.579287] [<c10f1cf6>] ? reiserfs_file_release+0x11d/0x344
[ 6136.579293] [<c10f1cf6>] reiserfs_file_release+0x11d/0x344
[ 6136.579299] [<c10a57bd>] ? fput+0x90/0x16a
[ 6136.579304] [<c10a580d>] fput+0xe0/0x16a
[ 6136.579309] [<c1090ca6>] remove_vma+0x28/0x47
[ 6136.579314] [<c1091819>] ? arch_unmap_area_topdown+0x0/0x18
[ 6136.579319] [<c1091a68>] do_munmap+0x1e8/0x200
[ 6136.579325] [<c1091b93>] sys_munmap+0x32/0x42
[ 6136.579330] [<c10027d3>] sysenter_do_call+0x12/0x32



So, below is the simple code which produces similar result:

[ 573.405720]
[ 573.405722] =======================================================
[ 573.405728] [ INFO: possible circular locking dependency detected ]
[ 573.405732] 2.6.35-rc3-dbg-git6-00502-g94feaba-dirty #65
[ 573.405735] -------------------------------------------------------
[ 573.405739] a.out/7287 is trying to acquire lock:
[ 573.405742] (&sb->s_type->i_mutex_key#10){+.+.+.}, at: [<c10f1d4e>] reiserfs_file_release+0x11d/0x344
[ 573.405758]
[ 573.405759] but task is already holding lock:
[ 573.405762] (&mm->mmap_sem){++++++}, at: [<c1092937>] sys_mmap_pgoff+0xa4/0xe7
[ 573.405772]
[ 573.405773] which lock already depends on the new lock.
[ 573.405774]
[ 573.405777]
[ 573.405778] the existing dependency chain (in reverse order) is:
[ 573.405781]
[ 573.405782] -> #1 (&mm->mmap_sem){++++++}:
[ 573.405789] [<c104f566>] lock_acquire+0x59/0x70
[ 573.405797] [<c108cf70>] might_fault+0x53/0x70
[ 573.405803] [<c1185418>] copy_to_user+0x30/0x48
[ 573.405809] [<c10afaf9>] filldir64+0x95/0xc9
[ 573.405815] [<c10f255c>] reiserfs_readdir_dentry+0x35d/0x4d9
[ 573.405821] [<c10f26ea>] reiserfs_readdir+0x12/0x17
[ 573.405827] [<c10afd17>] vfs_readdir+0x6d/0x92
[ 573.405831] [<c10afe91>] sys_getdents64+0x63/0xa2
[ 573.405836] [<c10027d3>] sysenter_do_call+0x12/0x32
[ 573.405843]
[ 573.405843] -> #0 (&sb->s_type->i_mutex_key#10){+.+.+.}:
[ 573.405851] [<c104ef5c>] __lock_acquire+0x96d/0xbe1
[ 573.405857] [<c104f566>] lock_acquire+0x59/0x70
[ 573.405862] [<c12c5674>] __mutex_lock_common+0x39/0x36b
[ 573.405869] [<c12c59e0>] mutex_lock_nested+0x12/0x15
[ 573.405874] [<c10f1d4e>] reiserfs_file_release+0x11d/0x344
[ 573.405880] [<c10a5805>] fput+0xe0/0x16a
[ 573.405886] [<c1090c9e>] remove_vma+0x28/0x47
[ 573.405892] [<c1091a60>] do_munmap+0x1e8/0x200
[ 573.405897] [<c109230a>] mmap_region+0x6b/0x372
[ 573.405902] [<c109284d>] do_mmap_pgoff+0x23c/0x282
[ 573.405908] [<c1092950>] sys_mmap_pgoff+0xbd/0xe7
[ 573.405913] [<c10027d3>] sysenter_do_call+0x12/0x32
[ 573.405919]
[ 573.405920] other info that might help us debug this:
[ 573.405921]
[ 573.405925] 1 lock held by a.out/7287:
[ 573.405928] #0: (&mm->mmap_sem){++++++}, at: [<c1092937>] sys_mmap_pgoff+0xa4/0xe7
[ 573.405937]
[ 573.405938] stack backtrace:
[ 573.405942] Pid: 7287, comm: a.out Not tainted 2.6.35-rc3-dbg-git6-00502-g94feaba-dirty #65
[ 573.405946] Call Trace:
[ 573.405951] [<c12c48f3>] ? printk+0xf/0x11
[ 573.405957] [<c104dc09>] print_circular_bug+0x8a/0x96
[ 573.405962] [<c104ef5c>] __lock_acquire+0x96d/0xbe1
[ 573.405969] [<c104e462>] ? mark_lock+0x26/0x1b3
[ 573.405975] [<c104f566>] lock_acquire+0x59/0x70
[ 573.405980] [<c10f1d4e>] ? reiserfs_file_release+0x11d/0x344
[ 573.405986] [<c12c5674>] __mutex_lock_common+0x39/0x36b
[ 573.405991] [<c10f1d4e>] ? reiserfs_file_release+0x11d/0x344
[ 573.405997] [<c12c59e0>] mutex_lock_nested+0x12/0x15
[ 573.406003] [<c10f1d4e>] ? reiserfs_file_release+0x11d/0x344
[ 573.406008] [<c10f1d4e>] reiserfs_file_release+0x11d/0x344
[ 573.406014] [<c10a57b5>] ? fput+0x90/0x16a
[ 573.406019] [<c10a5805>] fput+0xe0/0x16a
[ 573.406024] [<c1090c9e>] remove_vma+0x28/0x47
[ 573.406030] [<c1091811>] ? arch_unmap_area_topdown+0x0/0x18
[ 573.406035] [<c1091a60>] do_munmap+0x1e8/0x200
[ 573.406040] [<c109230a>] mmap_region+0x6b/0x372
[ 573.406046] [<c109284d>] do_mmap_pgoff+0x23c/0x282
[ 573.406052] [<c1092950>] sys_mmap_pgoff+0xbd/0xe7
[ 573.406058] [<c10027d3>] sysenter_do_call+0x12/0x32


As well as this:

[ 202.300464] REISERFS error (device sda9): vs-2100 add_save_link:
search_by_key ([-1 7812832 0x1 IND]) returned 1
[ 202.300473] REISERFS (device sda9): Remounting filesystem read-only
[ 202.301603] ------------[ cut here ]------------
[ 202.301615] WARNING: at fs/reiserfs/journal.c:3436
journal_end+0x5b/0xaf()
[ 202.301619] Hardware name: F3JC
[ 202.301622] Modules linked in: snd_seq_dummy snd_seq_oss
snd_seq_midi_event snd_seq snd_seq_device snd_hda_codec_si3054
snd_hda_codec_realtek snd_hwdep snd_pcm_oss snd_mixer_oss asus_laptop
sparse_keymap sdhci_pci sdhci snd_hda_intel mmc_core led_class snd_hda_codec
rng_core snd_pcm snd_timer snd_page_alloc snd i2c_i801 soundcore psmouse sg
evdev serio_raw r8169 mii usbhid hid uhci_hcd ehci_hcd sr_mod usbcore cdrom
sd_mod ata_piix
[ 202.301689] Pid: 5055, comm: a.out Not tainted
2.6.35-rc3-dbg-git6-00502-g94feaba-dirty #65
[ 202.301693] Call Trace:
[ 202.301701] [<c102e3a2>] warn_slowpath_common+0x65/0x7a
[ 202.301707] [<c1102d95>] ? journal_end+0x5b/0xaf
[ 202.301712] [<c102e3c6>] warn_slowpath_null+0xf/0x13
[ 202.301718] [<c1102d95>] journal_end+0x5b/0xaf
[ 202.301725] [<c10eebaa>] reiserfs_truncate_file+0x19f/0x233
[ 202.301733] [<c10f1ba1>] reiserfs_vfs_truncate_file+0xd/0xf
[ 202.301738] [<c1084883>] vmtruncate+0x23/0x29
[ 202.301745] [<c10b4ad4>] inode_setattr+0x47/0x68
[ 202.301751] [<c10f1b3f>] reiserfs_setattr+0x242/0x297
[ 202.301758] [<c12c5d05>] ? down_write+0x22/0x2a
[ 202.301764] [<c10b4d6f>] notify_change+0x15c/0x26b
[ 202.301770] [<c10a35c7>] do_truncate+0x64/0x7d
[ 202.301776] [<c12c69b0>] ? _raw_spin_unlock+0x33/0x3f
[ 202.301783] [<c10ad892>] do_last+0x450/0x459
[ 202.301789] [<c10ada5b>] do_filp_open+0x1c0/0x41a
[ 202.301798] [<c1029081>] ? get_parent_ip+0xb/0x31
[ 202.301804] [<c1029123>] ? sub_preempt_count+0x7c/0x89
[ 202.301810] [<c10b5746>] ? alloc_fd+0xb4/0xbf
[ 202.301816] [<c10a3f46>] do_sys_open+0x48/0xdf
[ 202.301821] [<c10a3ffb>] sys_open+0x1e/0x26
[ 202.301827] [<c10027d3>] sysenter_do_call+0x12/0x32
[ 202.301833] ---[ end trace c4e3312bdadd2dc5 ]---
[ 202.301864] REISERFS warning (device sda9): clm-6006
reiserfs_dirty_inode: writing inode 7812832 on readonly FS
[ 202.302011] REISERFS warning (device sda9): clm-6006
reiserfs_dirty_inode: writing inode 7812832 on readonly FS
[ 202.302396] ------------[ cut here ]------------
[ 202.302403] WARNING: at fs/reiserfs/journal.c:3436
journal_end+0x5b/0xaf()
[ 202.302406] Hardware name: F3JC
[ 202.302409] Modules linked in: snd_seq_dummy snd_seq_oss
snd_seq_midi_event snd_seq snd_seq_device snd_hda_codec_si3054
snd_hda_codec_realtek snd_hwdep snd_pcm_oss snd_mixer_oss asus_laptop
sparse_keymap sdhci_pci sdhci snd_hda_intel mmc_core led_class snd_hda_codec
rng_core snd_pcm snd_timer snd_page_alloc snd i2c_i801 soundcore psmouse sg
evdev serio_raw r8169 mii usbhid hid uhci_hcd ehci_hcd sr_mod usbcore cdrom
sd_mod ata_piix
[ 202.302466] Pid: 4951, comm: a.out Tainted: G W
2.6.35-rc3-dbg-git6-00502-g94feaba-dirty #65
[ 202.302470] Call Trace:
[ 202.302476] [<c102e3a2>] warn_slowpath_common+0x65/0x7a
[ 202.302481] [<c1102d95>] ? journal_end+0x5b/0xaf
[ 202.302487] [<c102e3c6>] warn_slowpath_null+0xf/0x13
[ 202.302492] [<c1102d95>] journal_end+0x5b/0xaf
[ 202.302497] [<c10fd687>] ? reiserfs_delete_object+0x29/0x60
[ 202.302503] [<c10ee1ee>] reiserfs_delete_inode+0xc4/0x100
[ 202.302510] [<c10b4265>] generic_delete_inode+0x72/0xc2
[ 202.302515] [<c10b42c6>] generic_drop_inode+0x11/0x4c
[ 202.302520] [<c10b37ff>] iput+0x49/0x4c
[ 202.302525] [<c10b165e>] dentry_iput+0x9a/0xb3
[ 202.302530] [<c10b16a4>] d_kill+0x2d/0x47
[ 202.302534] [<c10b1c94>] dput+0xdf/0xe8
[ 202.302540] [<c10a5872>] fput+0x14d/0x16a
[ 202.302546] [<c1090c9e>] remove_vma+0x28/0x47
[ 202.302551] [<c1091c29>] exit_mmap+0x8e/0xa6
[ 202.302556] [<c102c4b3>] mmput+0x24/0xab
[ 202.302561] [<c102fd83>] exit_mm+0xe8/0xf0
[ 202.302567] [<c1031295>] do_exit+0x1b7/0x5cb
[ 202.302573] [<c10434a6>] ? up_read+0x1d/0x23
[ 202.302578] [<c10318b3>] do_group_exit+0x60/0x83
[ 202.302584] [<c10318e9>] sys_exit_group+0x13/0x17
[ 202.302589] [<c10027d3>] sysenter_do_call+0x12/0x32
[ 202.302594] ---[ end trace c4e3312bdadd2dc6 ]---



==== code ====

conftest.c


/*

2010, Sergey Senozhatsky. GPLv2

Description:
We have several PIDs working with conftest.mmap.
Actually this is (seems) what hapenning during emacs configure.

traced emacs configure:

vfork() ...
====
... PID 5446

5446 open("conftest.mmap", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE, 0600) = 3
write(3,
"g\306isQ\377J\354)\315\272\253\362\373\343F|\302T\370\33\350\347\215vZ.c3\237\311\232"...,
4096) = 4096
close(3) = 0
open("conftest.txt", O_RDWR|O_CREAT|O_TRUNC|O_LARGEFILE, 0600) = 3
write(3, "\0", 1) = 1
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_SHARED, 3, 0) = 0xb78a8000
close(3) = 0
munmap(0xb78a8000, 4096) = 0
open("conftest.mmap", O_RDWR|O_LARGEFILE) = 3
mmap2(0xb78a8000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED,
3, 0) = 0xb78a8000
read(3,
"*****"...,
4096) = 4096
close(3) = 0

open(".", O_RDONLY|O_LARGEFILE) = 3
close(3) = 0
fstatat64(AT_FDCWD, "conftest.mmap", {st_mode=S_IFREG|0600,
st_size=4096, ...}, AT_SYMLINK_NOFOLLOW) = 0
unlinkat(AT_FDCWD, "conftest.mmap", 0) = 0

====
... PID 5449
5449 fstatat64(AT_FDCWD, "conftest.mmap", {st_mode=S_IFREG|0600, st_size=4096, ...}, AT_SYMLINK_NOFOLLOW) = 0
5449 unlinkat(AT_FDCWD, "conftest.mmap", 0) = 0
5449 execve("/bin/rm", ["rm", "-f", "conftest.mmap", "conftest.txt"]
..
*/

/*
The code below produces:
[ 46.727489] =======================================================
[ 46.727495] [ INFO: possible circular locking dependency detected ]
[ 46.727499] 2.6.35-rc3-dbg-git5-00446-g36336bc-dirty #64
[ 46.727503] -------------------------------------------------------
[ 46.727506] a.out/5840 is trying to acquire lock:
[ 46.727510] (&sb->s_type->i_mutex_key#10){+.+.+.}, at: [<c10f1d5c>] reiserfs_file_release+0x12b/0x367
[ 46.727526]
[ 46.727527] but task is already holding lock:
[ 46.727530] (&mm->mmap_sem){++++++}, at: [<c1092937>] sys_mmap_pgoff+0xa4/0xe7
[ 46.727540]
[ 46.727541] which lock already depends on the new lock.
[ 46.727543]
[ 46.727546]
[ 46.727546] the existing dependency chain (in reverse order) is:
[ 46.727550]
[ 46.727551] -> #1 (&mm->mmap_sem){++++++}:
[ 46.727557] [<c104f566>] lock_acquire+0x59/0x70
[ 46.727565] [<c108cf70>] might_fault+0x53/0x70
[ 46.727571] [<c1185438>] copy_to_user+0x30/0x48
[ 46.727578] [<c10afaf9>] filldir64+0x95/0xc9
[ 46.727584] [<c10f257c>] reiserfs_readdir_dentry+0x35d/0x4d9
[ 46.727590] [<c10f270a>] reiserfs_readdir+0x12/0x17
[ 46.727596] [<c10afd17>] vfs_readdir+0x6d/0x92
[ 46.727600] [<c10afe91>] sys_getdents64+0x63/0xa2
[ 46.727606] [<c10027d3>] sysenter_do_call+0x12/0x32
[ 46.727612]
[ 46.727613] -> #0 (&sb->s_type->i_mutex_key#10){+.+.+.}:
[ 46.727621] [<c104ef5c>] __lock_acquire+0x96d/0xbe1
[ 46.727626] [<c104f566>] lock_acquire+0x59/0x70
[ 46.727632] [<c12c5694>] __mutex_lock_common+0x39/0x36b
[ 46.727639] [<c12c5a00>] mutex_lock_nested+0x12/0x15
[ 46.727644] [<c10f1d5c>] reiserfs_file_release+0x12b/0x367
[ 46.727650] [<c10a5805>] fput+0xe0/0x16a
[ 46.727657] [<c1090c9e>] remove_vma+0x28/0x47
[ 46.727662] [<c1091a60>] do_munmap+0x1e8/0x200
[ 46.727667] [<c109230a>] mmap_region+0x6b/0x372
[ 46.727672] [<c109284d>] do_mmap_pgoff+0x23c/0x282
[ 46.727678] [<c1092950>] sys_mmap_pgoff+0xbd/0xe7
[ 46.727683] [<c10027d3>] sysenter_do_call+0x12/0x32
[ 46.727689]
[ 46.727690] other info that might help us debug this:
[ 46.727691]
[ 46.727695] 1 lock held by a.out/5840:
[ 46.727698] #0: (&mm->mmap_sem){++++++}, at: [<c1092937>] sys_mmap_pgoff+0xa4/0xe7
[ 46.727707]
[ 46.727708] stack backtrace:
[ 46.727713] Pid: 5840, comm: a.out Not tainted 2.6.35-rc3-dbg-git5-00446-g36336bc-dirty #64
[ 46.727717] Call Trace:
[ 46.727722] [<c12c4913>] ? printk+0xf/0x11
[ 46.727728] [<c104dc09>] print_circular_bug+0x8a/0x96
[ 46.727734] [<c104ef5c>] __lock_acquire+0x96d/0xbe1
[ 46.727740] [<c104ccc8>] ? look_up_lock_class+0x6c/0x7b
[ 46.727746] [<c104e462>] ? mark_lock+0x26/0x1b3
[ 46.727752] [<c104f566>] lock_acquire+0x59/0x70
[ 46.727758] [<c10f1d5c>] ? reiserfs_file_release+0x12b/0x367
[ 46.727764] [<c12c5694>] __mutex_lock_common+0x39/0x36b
[ 46.727769] [<c10f1d5c>] ? reiserfs_file_release+0x12b/0x367
[ 46.727775] [<c12c5a00>] mutex_lock_nested+0x12/0x15
[ 46.727781] [<c10f1d5c>] ? reiserfs_file_release+0x12b/0x367
[ 46.727786] [<c10f1d5c>] reiserfs_file_release+0x12b/0x367
[ 46.727792] [<c108d77d>] ? free_pgd_range+0x96/0x12f
[ 46.727798] [<c10a57b5>] ? fput+0x90/0x16a
[ 46.727803] [<c10a5805>] fput+0xe0/0x16a
[ 46.727808] [<c1090c9e>] remove_vma+0x28/0x47
[ 46.727814] [<c1091811>] ? arch_unmap_area_topdown+0x0/0x18
[ 46.727819] [<c1091a60>] do_munmap+0x1e8/0x200
[ 46.727825] [<c109230a>] mmap_region+0x6b/0x372
[ 46.727831] [<c109284d>] do_mmap_pgoff+0x23c/0x282
[ 46.727837] [<c1092950>] sys_mmap_pgoff+0xbd/0xe7
[ 46.727842] [<c10027d3>] sysenter_do_call+0x12/0x32


*/

#define _GNU_SOURCE

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/mman.h>

int main()
{
char buf[4096];
int i = 0;
/* we don't really care */
for (; i < 4096; i++)
buf[i] = (i + 65) % 255;

for (i = 0; i < 10; i++) {

int pid = fork();
if (pid > 0 ) {
printf("parent...");
} else if (pid == 0) {

printf("child...\n");
int fd = open("conftest.mmap", O_WRONLY|O_CREAT|O_TRUNC|O_LARGEFILE, 0600);
if (fd > 0) {
printf("OPEN ok %d\n", fd);
if (write(fd, buf, 4096) < 0)
printf("WRITE error\n");
else
printf("WRITE ok\n");

close(fd);
} else {
printf("OPEN error\n");
}

fd = open("conftest.mmap", O_RDWR|O_LARGEFILE);
if (fd > 0) {
printf("OPEN conftest.mmap %d\n", fd);

void *map = mmap((void*)0xb78a8000, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_FIXED, fd, 0);
if (map == MAP_FAILED) {
printf("MMAP failed\n");
goto out;
} else {
printf("MMAP ok\n");
}

if (read(fd, buf, 4096) < 0)
printf("READ failed\n");
else
printf("READ ok\n");
close(fd);

} else {
printf("Error: can't open conftest.mmap\n");
}

out:
fd = open(".", O_RDONLY|O_LARGEFILE);
if (fd > 0) {
printf("OPEN . ok %d... closing\n", fd);
close(fd);
} else {
printf("OPEN error\n");
}

struct stat _stat;
if (fstatat(AT_FDCWD, "conftest.mmap", &_stat, AT_SYMLINK_NOFOLLOW) < 0)
printf("FSTATAT error\n");
else
printf("FSTATAT ok\n");

if (unlinkat(AT_FDCWD, "conftest.mmap", 0) < 0)
printf("UNLINKAT error\n");
else
printf("UNLINKAT ok\n");

} else {
printf("FORK error\n");
}
}

return 0;
}


Attachment: pgp00000.pgp
Description: PGP signature