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From: Dave Chinner <david@fromorbit.com>
To: Eric Sandeen <sandeen@sandeen.net>
Cc: xfs@oss.sgi.com
Subject: Re: Pass mp to kmem_alloc and friends?
Date: Thu, 21 Jan 2016 07:32:11 +1100	[thread overview]
Message-ID: <20160120203211.GC20456@dastard> (raw)
In-Reply-To: <569FCAED.4050306@sandeen.net>

On Wed, Jan 20, 2016 at 11:59:09AM -0600, Eric Sandeen wrote:
> I had a request for the kmem_alloc deadlock warning to print the
> filesystem involved.
> 
> Any objections to passing mp into kmem_alloc() and friends whenever
> it's reasonably available from the caller?
> 
> It'd be a big mechanical change, don't want to embark on that unless
> it seems acceptable & useful.

I think I hinted at this in the configurable error handling patchset
I have so that we could have configurable ENOMEM error handling. My
comment in the current commit message for that patch includes this:

| I'm not yet sure how to hook it into the memory allocation calls -
| that will be done in a later patch; this just demonstrates how
| multiple classes are configured and initialised. It may be that we
| don't configure specific errors here - instead configure how we
| handle specific types of allocation failure e.g. GFP_KERNEL vs
| GFP_NOFS vs allocations inside transactions. Either way, we are
| going to need to plumb the error config handler into the
| memory allocation code in some manner.

So I think we are going to have to plumb the xfs_mount into these
calls at some point in the near future.

> I think we generally know the root causes of the most common deadlock
> warnings, but it's a warm fuzzy to give as much info as possible.
> 
> Heck, I almost wonder if passing a descriptive string in, for at
> least the problematic cases we know about, i.e. "extent map realloc"
> so we'd get something like:
> 
> XFS (sdb1): myprocess(123) possible memory allocation deadlock size 12345 during extent map realloc in kmem_alloc (mode:0x250)

If we want more context, then make it an error message that can dump
the stack when the error level is turned up. i.e. if we pass in an
xfs_mount, we can use XFS_ERROR_REPORT here...

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

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      parent reply	other threads:[~2016-01-20 20:32 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-01-20 17:59 Pass mp to kmem_alloc and friends? Eric Sandeen
2016-01-20 19:53 ` Darrick J. Wong
2016-01-20 20:35   ` Dave Chinner
2016-01-20 20:32 ` Dave Chinner [this message]

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