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authorEric W. Biederman <ebiederm@xmission.com>2006-06-26 03:25:55 -0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-06-26 12:58:25 -0400
commit99f895518368252ba862cc15ce4eb98ebbe1bec6 (patch)
treea9dcc01963221d1fd6a7e357b95d361ebfe91c6d /include
parent8578cea7509cbdec25b31d08b48a92fcc3b1a9e3 (diff)
[PATCH] proc: don't lock task_structs indefinitely
Every inode in /proc holds a reference to a struct task_struct. If a directory or file is opened and remains open after the the task exits this pinning continues. With 8K stacks on a 32bit machine the amount pinned per file descriptor is about 10K. Normally I would figure a reasonable per user process limit is about 100 processes. With 80 processes, with a 1000 file descriptors each I can trigger the 00M killer on a 32bit kernel, because I have pinned about 800MB of useless data. This patch replaces the struct task_struct pointer with a pointer to a struct task_ref which has a struct task_struct pointer. The so the pinning of dead tasks does not happen. The code now has to contend with the fact that the task may now exit at any time. Which is a little but not muh more complicated. With this change it takes about 1000 processes each opening up 1000 file descriptors before I can trigger the OOM killer. Much better. [mlp@google.com: task_mmu small fixes] Signed-off-by: Eric W. Biederman <ebiederm@xmission.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: Paul Jackson <pj@sgi.com> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Albert Cahalan <acahalan@gmail.com> Signed-off-by: Prasanna Meda <mlp@google.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include')
-rw-r--r--include/linux/proc_fs.h8
1 files changed, 7 insertions, 1 deletions
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index d4d2081dbaf7..4c7271f04697 100644
--- a/include/linux/proc_fs.h
+++ b/include/linux/proc_fs.h
@@ -246,7 +246,7 @@ extern void kclist_add(struct kcore_list *, void *, size_t);
246#endif 246#endif
247 247
248struct proc_inode { 248struct proc_inode {
249 struct task_struct *task; 249 struct task_ref *tref;
250 int fd; 250 int fd;
251 union { 251 union {
252 int (*proc_get_link)(struct inode *, struct dentry **, struct vfsmount **); 252 int (*proc_get_link)(struct inode *, struct dentry **, struct vfsmount **);
@@ -266,4 +266,10 @@ static inline struct proc_dir_entry *PDE(const struct inode *inode)
266 return PROC_I(inode)->pde; 266 return PROC_I(inode)->pde;
267} 267}
268 268
269struct proc_maps_private {
270 struct task_ref *tref;
271 struct task_struct *task;
272 struct vm_area_struct *tail_vma;
273};
274
269#endif /* _LINUX_PROC_FS_H */ 275#endif /* _LINUX_PROC_FS_H */