linux/fs/proc
Oleg Nesterov 9b4d1cbef8 proc_flush_task: flush /proc/tid/task/pid when a sub-thread exits
The exiting sub-thread flushes /proc/pid only, but this doesn't buy too
much: ps and friends mostly use /proc/tid/task/pid.

Remove "if (thread_group_leader())" checks from proc_flush_task() path,
this means we always remove /proc/tid/task/pid dentry on exit, and this
actually matches the comment above proc_flush_task().

The test-case:

	static void* tfunc(void *arg)
	{
		char name[256];

		sprintf(name, "/proc/%d/task/%ld/status", getpid(), gettid());
		close(open(name, O_RDONLY));

		return NULL;
	}

	int main(void)
	{
		pthread_t t;

		for (;;) {
			if (!pthread_create(&t, NULL, &tfunc, NULL))
				pthread_join(t, NULL);
		}
	}

slabtop shows that pid/proc_inode_cache/etc grow quickly and
"indefinitely" until the task is killed or shrink_slab() is called, not
good.  And the main thread needs a lot of time to exit.

The same can happen if something like "ps -efL" runs continuously, while
some application spawns short-living threads.

Reported-by: "James M. Leddy" <jleddy@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Dominic Duval <dduval@redhat.com>
Cc: Frank Hirtz <fhirtz@redhat.com>
Cc: "Fuller, Johnray" <Johnray.Fuller@gs.com>
Cc: Larry Woodman <lwoodman@redhat.com>
Cc: Paul Batkowski <pbatkowski@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-09-23 07:39:40 -07:00
..
array.c proc: avoid information leaks to non-privileged processes 2009-05-04 15:14:23 -07:00
base.c proc_flush_task: flush /proc/tid/task/pid when a sub-thread exits 2009-09-23 07:39:40 -07:00
cmdline.c proc: switch /proc/cmdline to seq_file 2008-10-23 14:29:04 +04:00
cpuinfo.c proc: move /proc/cpuinfo code to fs/proc/cpuinfo.c 2008-10-23 15:05:11 +04:00
devices.c proc: move /proc/devices code to fs/proc/devices.c 2008-10-23 15:02:18 +04:00
generic.c proc 1/2: do PDE usecounting even for ->read_proc, ->write_proc 2009-03-31 01:14:27 +04:00
inode.c proc 2/2: remove struct proc_dir_entry::owner 2009-03-31 01:14:44 +04:00
internal.h Move junk from proc_fs.h to fs/proc/internal.h 2009-06-11 21:36:01 -04:00
interrupts.c proc: move /proc/interrupts boilerplate code to fs/proc/interrupts.c 2008-10-23 15:15:46 +04:00
Kconfig proc: move PROC_PAGE_MONITOR to fs/proc/Kconfig 2008-10-10 04:18:57 +04:00
kcore.c kcore: /proc/kcore should use vread 2009-09-22 07:17:34 -07:00
kmsg.c proc: move /proc/kmsg creation to fs/proc/kmsg.c 2008-10-23 14:35:08 +04:00
loadavg.c sched, timers: cleanup avenrun users 2009-05-15 15:32:45 +02:00
Makefile proc: export statistics for softirq to /proc 2009-06-18 13:03:41 -07:00
meminfo.c mm: oom analysis: add shmem vmstat 2009-09-22 07:17:27 -07:00
mmu.c fs/proc/mmu.c: headers butchery 2007-10-17 08:42:48 -07:00
nommu.c seq_file: constify seq_operations 2009-09-23 07:39:29 -07:00
page.c ksm: identify PageKsm pages 2009-09-22 07:17:31 -07:00
proc_devtree.c procfs: remove sparse errors in proc_devtree.c 2009-06-18 13:03:41 -07:00
proc_net.c proc: stop using BKL 2009-01-05 12:27:44 +03:00
proc_sysctl.c constify dentry_operations: procfs 2009-03-27 14:44:01 -04:00
proc_tty.c proc tty: remove struct tty_operations::read_proc 2009-04-01 08:59:10 -07:00
root.c Convert obvious places to deactivate_locked_super() 2009-05-09 10:49:40 -04:00
softirqs.c proc: export statistics for softirq to /proc 2009-06-18 13:03:41 -07:00
stat.c proc: export statistics for softirq to /proc 2009-06-18 13:03:41 -07:00
task_mmu.c pagemap clear_refs: modify to specify anon or mapped vma clearing 2009-09-22 07:17:33 -07:00
task_nommu.c mm_for_maps: shift down_read(mmap_sem) to the caller 2009-08-10 20:48:32 +10:00
uptime.c Revert "proc: revert /proc/uptime to ->read_proc hook" 2009-03-31 01:14:58 +04:00
version.c proc: switch /proc/version to seq_file 2008-10-23 14:19:58 +04:00
vmcore.c proc: vmcore - use kzalloc in get_new_element() 2009-06-18 13:03:41 -07:00