linux-kernel - Re: [PATCH] vmalloc: add warning in _

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Date:	Wed, 2 May 2012 22:46:12 -0700 (PDT)
From:	Sage Weil <sage@...dream.net>
To:	Minchan Kim <minchan@...nel.org>
cc:	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, kosaki.motohiro@...il.com,
	rientjes@...gle.com, Neil Brown <neilb@...e.de>,
	Artem Bityutskiy <dedekind1@...il.com>,
	David Woodhouse <dwmw2@...radead.org>,
	Theodore Ts'o <tytso@....edu>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Steven Whitehouse <swhiteho@...hat.com>,
	"David S. Miller" <davem@...emloft.net>,
	James Morris <jmorris@...ei.org>,
	Alexander Viro <viro@...iv.linux.org.uk>
Subject: Re: [PATCH] vmalloc: add warning in __vmalloc

On Thu, 3 May 2012, Minchan Kim wrote:
> On 05/03/2012 04:46 AM, Andrew Morton wrote:
> > Well.  What are we actually doing here?  Causing the kernel to spew a
> > warning due to known-buggy callsites, so that users will report the
> > warnings, eventually goading maintainers into fixing their stuff.
> > 
> > This isn't very efficient :(
> 
> 
> Yes. I hope maintainers fix it before merging this.
> 
> > 
> > It would be better to fix that stuff first, then add the warning to
> > prevent reoccurrences.  Yes, maintainers are very naughty and probably
> > do need cattle prods^W^W warnings to motivate them to fix stuff, but we
> > should first make an effort to get these things fixed without
> > irritating and alarming our users.  
> > 
> > Where are these offending callsites?

Okay, maybe this is a stupid question, but: if an fs can't call vmalloc 
with GFP_NOFS without risking deadlock, calling with GFP_KERNEL instead 
doesn't fix anything (besides being more honest).  This really means that 
vmalloc is effectively off-limits for file systems in any 
writeback-related path, right?

sage


> 
> 
> dm:
> __alloc_buffer_wait_no_callback
> 
> ubi:
> ubi_dbg_check_write
> ubi_dbg_check_all_ff
> 
> ext4 :
> ext4_kvmalloc
> 
> gfs2 :
> gfs2_alloc_sort_buffer
> 
> ntfs :
> __ntfs_malloc
> 
> ubifs :
> dbg_dump_leb
> scan_check_cb
> dump_lpt_leb
> dbg_check_ltab_lnum
> dbg_scan_orphans
> 
> mm :
> alloc_large_system_hash
> 
> ceph :
> fill_inode
> ceph_setxattr
> ceph_removexattr
> ceph_x_build_authorizer
> ceph_decode_buffer
> ceph_alloc_middle
> 
> 
> 
> > 
> > --
> > To unsubscribe, send a message with 'unsubscribe linux-mm' in
> > the body to majordomo@...ck.org.  For more info on Linux MM,
> > see: http://www.linux-mm.org/ .
> > Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
> > Don't email: <a href=mailto:"dont@...ck.org"> email@...ck.org </a>
> > 
> 
> 
> 
> -- 
> Kind regards,
> Minchan Kim
> 
> 
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