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linux/fs/proc
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Eric W. Biederman dfb2ea45be proc: Allow proc_free_inum to be called from any context 
While testing the pid namespace code I hit this nasty warning.

[  176.262617] ------------[ cut here ]------------
[  176.263388] WARNING: at /home/eric/projects/linux/linux-userns-devel/kernel/softirq.c:160 local_bh_enable_ip+0x7a/0xa0()
[  176.265145] Hardware name: Bochs
[  176.265677] Modules linked in:
[  176.266341] Pid: 742, comm: bash Not tainted 3.7.0userns+ #18
[  176.266564] Call Trace:
[  176.266564]  [<ffffffff810a539f>] warn_slowpath_common+0x7f/0xc0
[  176.266564]  [<ffffffff810a53fa>] warn_slowpath_null+0x1a/0x20
[  176.266564]  [<ffffffff810ad9ea>] local_bh_enable_ip+0x7a/0xa0
[  176.266564]  [<ffffffff819308c9>] _raw_spin_unlock_bh+0x19/0x20
[  176.266564]  [<ffffffff8123dbda>] proc_free_inum+0x3a/0x50
[  176.266564]  [<ffffffff8111d0dc>] free_pid_ns+0x1c/0x80
[  176.266564]  [<ffffffff8111d195>] put_pid_ns+0x35/0x50
[  176.266564]  [<ffffffff810c608a>] put_pid+0x4a/0x60
[  176.266564]  [<ffffffff8146b177>] tty_ioctl+0x717/0xc10
[  176.266564]  [<ffffffff810aa4d5>] ? wait_consider_task+0x855/0xb90
[  176.266564]  [<ffffffff81086bf9>] ? default_spin_lock_flags+0x9/0x10
[  176.266564]  [<ffffffff810cab0a>] ? remove_wait_queue+0x5a/0x70
[  176.266564]  [<ffffffff811e37e8>] do_vfs_ioctl+0x98/0x550
[  176.266564]  [<ffffffff810b8a0f>] ? recalc_sigpending+0x1f/0x60
[  176.266564]  [<ffffffff810b9127>] ? __set_task_blocked+0x37/0x80
[  176.266564]  [<ffffffff810ab95b>] ? sys_wait4+0xab/0xf0
[  176.266564]  [<ffffffff811e3d31>] sys_ioctl+0x91/0xb0
[  176.266564]  [<ffffffff810a95f0>] ? task_stopped_code+0x50/0x50
[  176.266564]  [<ffffffff81939199>] system_call_fastpath+0x16/0x1b
[  176.266564] ---[ end trace 387af88219ad6143 ]---

It turns out that spin_unlock_bh(proc_inum_lock) is not safe when
put_pid is called with another spinlock held and irqs disabled.

For now take the easy path and use spin_lock_irqsave(proc_inum_lock)
in proc_free_inum and spin_loc_irq in proc_alloc_inum(proc_inum_lock).

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2012-12-25 16:23:12 -08:00
..
array.c Merge branch 'akpm' (Andrew's patch-bomb) 2012-12-17 20:58:12 -08:00
base.c procfs: drop vmtruncate 2012-12-20 14:00:01 -05:00
cmdline.c
consoles.c console: rename acquire/release_console_sem() to console_lock/unlock() 2011-01-26 10:50:06 +10:00
cpuinfo.c
devices.c proc: use seq_puts()/seq_putc() where possible 2011-01-13 08:03:16 -08:00
fd.c procfs: add ability to plug in auxiliary fdinfo providers 2012-12-17 17:15:27 -08:00
fd.h procfs: Move /proc/pid/fd[info] handling code to fd.[ch] 2012-09-26 21:10:01 -04:00
generic.c proc: Allow proc_free_inum to be called from any context 2012-12-25 16:23:12 -08:00
inode.c proc: Fix the namespace inode permission checks. 2012-11-20 04:19:48 -08:00
internal.h procfs: Use the proc generic infrastructure for proc/self. 2012-11-19 03:09:34 -08:00
interrupts.c
Kconfig kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT 2011-01-20 17:02:05 -08:00
kcore.c procfs: use N_MEMORY instead N_HIGH_MEMORY 2012-12-12 17:38:32 -08:00
kmsg.c procfs: Use generic_file_llseek in /proc/kmsg 2010-04-09 16:35:41 +02:00
loadavg.c
Makefile procfs: Use the proc generic infrastructure for proc/self. 2012-11-19 03:09:34 -08:00
meminfo.c fs/proc/meminfo.c: fix compilation error 2011-12-09 07:50:28 -08:00
mmu.c
namespaces.c proc: Usable inode numbers for the namespace file descriptors. 2012-11-20 04:19:49 -08:00
nommu.c include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h 2010-03-30 22:02:32 +09:00
page.c kpageflags: fix wrong KPF_THP on non-huge compound pages 2012-10-09 16:23:00 +09:00
proc_devtree.c procfs: use kbasename() 2012-12-17 17:15:17 -08:00
proc_net.c stop passing nameidata to ->lookup() 2012-07-14 16:34:32 +04:00
proc_sysctl.c procfs: drop vmtruncate 2012-12-20 14:00:01 -05:00
proc_tty.c proc: use seq_puts()/seq_putc() where possible 2011-01-13 08:03:16 -08:00
root.c userns: Allow unprivilged mounts of proc and sysfs 2012-11-20 04:19:18 -08:00
self.c procfs: Use the proc generic infrastructure for proc/self. 2012-11-19 03:09:34 -08:00
softirqs.c proc: use seq_puts()/seq_putc() where possible 2011-01-13 08:03:16 -08:00
stat.c nohz: Fix idle ticks in cpu summary line of /proc/stat 2012-10-10 14:05:21 +02:00
task_mmu.c procfs: add VmFlags field in smaps output 2012-12-17 17:15:22 -08:00
task_nommu.c proc: remove mm_for_maps() 2012-05-31 17:49:28 -07:00
uptime.c Merge branch 'sched/core' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip into cputime-tip 2011-12-19 19:23:15 +01:00
version.c
vmcore.c fadump: Introduce cleanup routine to invalidate /proc/vmcore. 2012-02-23 10:50:02 +11:00