Re: [PATCH] IB/sa: replace GFP_KERNEL with GFP_ATOMIC

From: Jason Gunthorpe
Date: Tue Oct 27 2015 - 14:17:08 EST

On Tue, Oct 27, 2015 at 02:12:36PM -0400, ira.weiny wrote:
> On Tue, Oct 27, 2015 at 09:17:40PM +0530, Saurabh Sengar wrote:
> > replace GFP_KERNEL with GFP_ATOMIC, as code while holding a spinlock
> > should be atomic
> > GFP_KERNEL may sleep and can cause deadlock, where as GFP_ATOMIC may
> > fail but certainly avoids deadlock
> Great catch. Thanks!
> However, gfp_t is passed to send_mad and we should pass that down and use it.

> spin_lock_irqsave(&ib_nl_request_lock, flags);
> - ret = ib_nl_send_msg(query);
> + ret = ib_nl_send_msg(query, gfp_mask);

A spin lock is guarenteed held around ib_nl_send_msg, so it's
allocations have to be atomic, can't use gfp_mask here..

I do wonder if it is a good idea to call ib_nl_send_msg with a spinlock
held though.. Would be nice to see that go away.

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