• Eric W. Biederman's avatar
    [PATCH] proc: don't lock task_structs indefinitely · 99f89551
    Eric W. Biederman authored
    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
    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: default avatarEric 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: default avatarPrasanna Meda <mlp@google.com>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
cpuset.c 71.7 KB