From mboxrd@z Thu Jan  1 00:00:00 1970
From: Nathan Lynch <ntl-e+AXbWqSrlAAvxtiuMwx3w@public.gmane.org>
Subject: Re: [RFC cr-pipe-v13][PATCH 2/3] Checkpoint open pipes
Date: Thu, 5 Feb 2009 20:26:37 -0600
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To: Cedric Le Goater <clg-NmTC/0ZBporQT0dZR+AlfA@public.gmane.org>
Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Dave Hansen <dave-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
List-Id: containers.vger.kernel.org

On Thu, 05 Feb 2009 10:45:55 +0100
Cedric Le Goater <clg-NmTC/0ZBporQT0dZR+AlfA@public.gmane.org> wrote:

> >  
> > +/* cr_write_pipebuf - dump contents of a pipe/fifo (assume i_mutex taken) */
> > +static int cr_write_pipebuf(struct cr_ctx *ctx, struct pipe_inode_info *pipe)
> > +{
> > +	struct cr_hdr h;
> > +	void *kbuf, *addr;
> > +	int i, ret = 0;
> > +
> > +	kbuf = (void *) __get_free_page(GFP_KERNEL);
> 
> this can sleep and inode->i_mutex is locked.

Generally, it is okay to perform operations that may sleep while
holding a mutex (not so with spinlocks, though).  Unless the page
allocator could try to acquire the same inode->i_mutex, this code
should be fine, no?