Messages in this thread | | | Date | Tue, 13 Mar 2012 15:40:17 +0100 | From | Jens Axboe <> | Subject | Re: [PATCH v2] block: fix ioc leak in put_io_context |
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On 03/13/2012 03:28 PM, Vivek Goyal wrote: > On Tue, Mar 13, 2012 at 01:21:06PM -0400, Xiaotian Feng wrote: >> When put_io_context is called, if ioc->icq_list is empty and refcount >> is 1, kernel will not free the ioc. >> >> This is caught by following kmemleak: >> >> unreferenced object 0xffff880036349fe0 (size 216): >> comm "sh", pid 2137, jiffies 4294931140 (age 290579.412s) >> hex dump (first 32 bytes): >> 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ >> 01 00 01 00 ad 4e ad de ff ff ff ff 00 00 00 00 .....N.......... >> backtrace: >> [<ffffffff8169f926>] kmemleak_alloc+0x26/0x50 >> [<ffffffff81195a9c>] kmem_cache_alloc_node+0x1cc/0x2a0 >> [<ffffffff81356b67>] create_io_context_slowpath+0x27/0x130 >> [<ffffffff81356d2b>] get_task_io_context+0xbb/0xf0 >> [<ffffffff81055f0e>] copy_process+0x188e/0x18b0 >> [<ffffffff8105609b>] do_fork+0x11b/0x420 >> [<ffffffff810247f8>] sys_clone+0x28/0x30 >> [<ffffffff816d3373>] stub_clone+0x13/0x20 >> [<ffffffffffffffff>] 0xffffffffffffffff >> >> ioc should be freed if ioc->icq_list is empty. >> Signed-off-by: Xiaotian Feng <dannyfeng@tencent.com> >> --- >> block/blk-ioc.c | 6 ++++++ >> 1 files changed, 6 insertions(+), 0 deletions(-) >> >> diff --git a/block/blk-ioc.c b/block/blk-ioc.c >> index 8b782a6..9690f27 100644 >> --- a/block/blk-ioc.c >> +++ b/block/blk-ioc.c >> @@ -145,6 +145,7 @@ static void ioc_release_fn(struct work_struct *work) >> void put_io_context(struct io_context *ioc) >> { >> unsigned long flags; >> + bool free_ioc = false; >> >> if (ioc == NULL) >> return; >> @@ -159,8 +160,13 @@ void put_io_context(struct io_context *ioc) >> spin_lock_irqsave(&ioc->lock, flags); >> if (!hlist_empty(&ioc->icq_list)) >> schedule_work(&ioc->release_work); >> + else >> + free_ioc = true; >> spin_unlock_irqrestore(&ioc->lock, flags); >> } >> + >> + if (free_ioc) >> + kmem_cache_free(iocontext_cachep, ioc); >> } >> EXPORT_SYMBOL(put_io_context); > > This one looks good to me. Tejun?
It's definitely a leak. I have applied it.
-- Jens Axboe
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