From: Roland Dreier <roland@kernel.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Joerg Roedel <joerg.roedel@amd.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] dma-debug: Fix deadlock with netconsole or other drivers that use the DMA API
Date: Thu, 19 Apr 2012 16:36:56 -0700 [thread overview]
Message-ID: <CAL1RGDXQ9NPKaNxBcNAYKknpSSScwXVa+gr8jXOFFU4ZjjSJ=A@mail.gmail.com> (raw)
In-Reply-To: <20120419114811.9e77accb.akpm@linux-foundation.org>
On Thu, Apr 19, 2012 at 11:48 AM, Andrew Morton
<akpm@linux-foundation.org> wrote:
> So *any* printk can deadlock if free_entries_lock is held and
> global_disable==false?
apparently.
> In that case we're going to need much sterner fixes. Any list_head
> operation can do a printk if list_head debugging is enabled.
> dma_debug_resize_entries() does a kfree() under free_entries_lock(!).
>
> Methinks we need a more general fix?
sigh... no good deed goes unpunished.
OK, will look at it. Just to make things even more fun, all the
err_printk() stuff can potentially deadlock on the hash bucket
lock, although that requires enough bad luck a collision to happen.
- R.
next prev parent reply other threads:[~2012-04-19 23:37 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-04-19 18:12 [PATCH] dma-debug: Fix deadlock with netconsole or other drivers that use the DMA API Roland Dreier
2012-04-19 18:48 ` Andrew Morton
2012-04-19 23:36 ` Roland Dreier [this message]
2012-04-19 23:50 ` Andrew Morton
2012-04-20 11:22 ` Joerg Roedel
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