Re: [RFC] iser-target: avoid reinitializing rdma contexts for isert commands

[Potnuri Bharat Teja <bharat@chelsio.com>]

On Wednesday, December 12/13/17, 2017 at 23:21:04 +0530, Jason Gunthorpe wrote:
> On Tue, Nov 28, 2017 at 11:58:07PM +0530, Bharat Potnuri wrote:
> > isert commands that failed during isert_rdma_rw_ctx_post() are queued to
> > Queue-Full(QF) queue and are scheduled to be reposted during queue-full
> > queue processing. During this reposting, the rdma contexts are initialised
> > again in isert_rdma_rw_ctx_post(), which is leaking significant memory.
> > 
> > unreferenced object 0xffff8830201d9640 (size 64):
> >   comm "kworker/0:2", pid 195, jiffies 4295374851 (age 4528.436s)
> >   hex dump (first 32 bytes):
> >     00 60 8b cb 2e 00 00 00 00 10 00 00 00 00 00 00  .`..............
> >     00 90 e3 cb 2e 00 00 00 00 10 00 00 00 00 00 00  ................
> >   backtrace:
> >     [<ffffffff8170711e>] kmemleak_alloc+0x4e/0xb0
> >     [<ffffffff811f8ba5>] __kmalloc+0x125/0x2b0
> >     [<ffffffffa046b24f>] rdma_rw_ctx_init+0x15f/0x6f0 [ib_core]
> >     [<ffffffffa07ab644>] isert_rdma_rw_ctx_post+0xc4/0x3c0 [ib_isert]
> >     [<ffffffffa07ad972>] isert_put_datain+0x112/0x1c0 [ib_isert]
> >     [<ffffffffa07dddce>] lio_queue_data_in+0x2e/0x30 [iscsi_target_mod]
> >     [<ffffffffa076c322>] target_qf_do_work+0x2b2/0x4b0 [target_core_mod]
> >     [<ffffffff81080c3b>] process_one_work+0x1db/0x5d0
> >     [<ffffffff8108107d>] worker_thread+0x4d/0x3e0
> >     [<ffffffff81088667>] kthread+0x117/0x150
> >     [<ffffffff81713fa7>] ret_from_fork+0x27/0x40
> >     [<ffffffffffffffff>] 0xffffffffffffffff
> > 
> > Here is patch to use the older rdma contexts while reposting
> > the isert commands intead of reinitialising them.
> > 
> > Signed-off-by: Potnuri Bharat Teja <bharat@chelsio.com>
> > Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
> >  drivers/infiniband/ulp/isert/ib_isert.c | 7 +++++++
> >  drivers/infiniband/ulp/isert/ib_isert.h | 1 +
> >  2 files changed, 8 insertions(+)
> >
> 
> So this RFC got Reviewed-by Sagi, is it to be applied now or something
> else??
> 
> If yes, what tree does it want to go through? I see Nicholas and Doug
> have both been historically taking isert patches.

Hi Jason,
Yes, this needs to be applied now, to the target-pending tree.
This fixes the "Queue-full handling" change that is already part of stable trees:
https://www.spinics.net/lists/target-devel/msg13574.html
This also needs to be tagged to stable trees.
As the Queue-full handling changes are already in linux, I think this can go 
through rdma tree aswell.

Thanks,
Bharat
> 
> Thanks,
> Jason
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