Messages in this thread | | | Date | Wed, 29 Jul 2009 19:36:58 -0500 | From | "Serge E. Hallyn" <> | Subject | Re: Possible memory leak via alloc_pid() |
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Quoting Andrew Morton (akpm@linux-foundation.org): > On Wed, 8 Jul 2009 22:33:31 +0100 > Catalin Marinas <catalin.marinas@arm.com> wrote: > > > Hi, > > > > There's a kmemleak report of a struct pid allocation in alloc_pid() > > which somehow gets lost: > > > > unreferenced object 0xc307aa00 (size 44): > > comm "gdm", pid 2734, jiffies 4294902040 > > backtrace: > > [<c01e721a>] create_object+0xfa/0x250 > > [<c01e73cd>] kmemleak_alloc+0x5d/0x70 > > [<c01e0ad6>] kmem_cache_alloc+0x156/0x1a0 > > [<c01552f9>] alloc_pid+0x19/0x350 > > [<c013e6e0>] copy_process+0x800/0x1230 > > [<c013f17f>] do_fork+0x6f/0x370 > > [<c0101986>] sys_clone+0x36/0x40 > > [<c010319c>] sysenter_do_call+0x12/0x38 > > [<ffffffff>] 0xffffffff > > > > This is the gdm fork for starting Xorg (with pid 2739). It first > > logged me in automatically, after which I logged out and gdm started > > another Xorg. The pid structure for the first Xorg is reported as a > > leak. The Xorg with pid 2739 is no longer present on my system. > > > > Using gdb vmlinux /proc/kcore shows that the pid->count is 2, so > > that's why it probably wasn't freed by put_pid(): > > > > (gdb) print ({struct pid}0xc307aa00) > > $20 = {count = {counter = 2}, level = 0, tasks = {{first = 0x0}, { > > first = 0x0}, {first = 0x0}}, rcu = {next = 0xc24bfd64, > > func = 0xc0154e90 <delayed_put_pid>}, numbers = {{nr = 2739, > > ns = 0xc0737540, pid_chain = {next = 0x0, pprev = 0x200200}}}} > > > > Note that kmemleak is aware of and scans pid_hash (which was recorded > > in kmemleak as a 16KB object). > > > > Thanks. Let's cc some recent pid fiddlers.
Hi,
thanks for the report. Note that kernel modules can increment those counds through find_get_pid(). Can you send your kernel .config and the output of lsmod?
thanks, -serge
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