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  9. Mar 07, 2009
    • Tejun Heo's avatar
      percpu: finer grained locking to break deadlock and allow atomic free · ccea34b5
      Tejun Heo authored 
      Impact: fix deadlock and allow atomic free

Percpu allocation always uses GFP_KERNEL and whole alloc/free paths
were protected by single mutex.  All percpu allocations have been from
GFP_KERNEL-safe context and the original allocator had this assumption
too.  However, by protecting both alloc and free paths with the same
mutex, the new allocator creates free -> alloc -> GFP_KERNEL
dependency which the original allocator didn't have.  This can lead to
deadlock if free is called from FS or IO paths.  Also, in general,
allocators are expected to allow free to be called from atomic
context.

This patch implements finer grained locking to break the deadlock and
allow atomic free.  For details, please read the "Synchronization
rules" comment.

While at it, also add CONTEXT: to function comments to describe which
context they expect to be called from and what they do to it.

This problem was reported by Thomas Gleixner and Peter Zijlstra.

  http://thread.gmane.org/gmane.linux.kernel/802384



Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Reported-by: default avatarThomas Gleixner <tglx@linutronix.de>
Reported-by: default avatarPeter Zijlstra <peterz@infradead.org>
      ccea34b5
    • Jeremy Higdon's avatar
      [IA64] fix PCI DMA flag propagation on SN (Altix) with PICs · c63c5805
      Jeremy Higdon authored 
      

We recently discovered a problem with passing of DMA attributes on SN
systems with the older PIC chips.

[akpm@linux-foundation.org: coding-style fixes]

Signed-off-by: default avatarJeremy Higdon <jeremy@sgi.com>
Cc: <habeck@sgi.com>
Cc: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarTony Luck <tony.luck@intel.com>
      c63c5805
    • Cyrill Gorcunov's avatar
      x86: linkage.h - guard assembler specifics by __ASSEMBLY__ · 7ab15247
      Cyrill Gorcunov authored 
      Stephen Rothwell reported:

|Today's linux-next build (x86_64 allmodconfig) produced this warning:
|
|In file included from drivers/char/epca.c:49:
|drivers/char/digiFep1.h:7:1: warning: "GLOBAL" redefined
|In file included from include/linux/linkage.h:5,
|                 from include/linux/kernel.h:11,
|                 from arch/x86/include/asm/system.h:10,
|                 from arch/x86/include/asm/processor.h:17,
|                 from include/linux/prefetch.h:14,
|                 from include/linux/list.h:6,
|                 from include/linux/module.h:9,
|                 from drivers/char/epca.c:29:
|arch/x86/include/asm/linkage.h:55:1: warning: this is the location of the previous definition
|
|Probably introduced by commit 95695547


|("x86: asm linkage - introduce GLOBAL macro") from the x86 tree.

Any assembler specific snippets being placed in headers
are to be protected by __ASSEMBLY__. Fixed.

Also move __ALIGN definition under the same protection as well.

Reported-by: default avatarStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: default avatarCyrill Gorcunov <gorcunov@openvz.org>
LKML-Reference: <20090306160833.GB7420@localhost>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      7ab15247
  11. Mar 06, 2009