Skip to content
  1. Dec 13, 2015
  3. Dec 12, 2015
  5. Dec 11, 2015
  7. Dec 05, 2015
  9. Dec 03, 2015
  11. Dec 01, 2015
  13. Nov 28, 2015
  15. Nov 24, 2015
  17. Nov 20, 2015
  19. Nov 19, 2015
  21. Nov 10, 2015
  23. Nov 07, 2015
    • Mel Gorman's avatar
      mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep... · d0164adc
      Mel Gorman authored 
      
mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd

__GFP_WAIT has been used to identify atomic context in callers that hold
spinlocks or are in interrupts.  They are expected to be high priority and
have access one of two watermarks lower than "min" which can be referred
to as the "atomic reserve".  __GFP_HIGH users get access to the first
lower watermark and can be called the "high priority reserve".

Over time, callers had a requirement to not block when fallback options
were available.  Some have abused __GFP_WAIT leading to a situation where
an optimisitic allocation with a fallback option can access atomic
reserves.

This patch uses __GFP_ATOMIC to identify callers that are truely atomic,
cannot sleep and have no alternative.  High priority users continue to use
__GFP_HIGH.  __GFP_DIRECT_RECLAIM identifies callers that can sleep and
are willing to enter direct reclaim.  __GFP_KSWAPD_RECLAIM to identify
callers that want to wake kswapd for background reclaim.  __GFP_WAIT is
redefined as a caller that is willing to enter direct reclaim and wake
kswapd for background reclaim.

This patch then converts a number of sites

o __GFP_ATOMIC is used by callers that are high priority and have memory
  pools for those requests. GFP_ATOMIC uses this flag.

o Callers that have a limited mempool to guarantee forward progress clear
  __GFP_DIRECT_RECLAIM but keep __GFP_KSWAPD_RECLAIM. bio allocations fall
  into this category where kswapd will still be woken but atomic reserves
  are not used as there is a one-entry mempool to guarantee progress.

o Callers that are checking if they are non-blocking should use the
  helper gfpflags_allow_blocking() where possible. This is because
  checking for __GFP_WAIT as was done historically now can trigger false
  positives. Some exceptions like dm-crypt.c exist where the code intent
  is clearer if __GFP_DIRECT_RECLAIM is used instead of the helper due to
  flag manipulations.

o Callers that built their own GFP flags instead of starting with GFP_KERNEL
  and friends now also need to specify __GFP_KSWAPD_RECLAIM.

The first key hazard to watch out for is callers that removed __GFP_WAIT
and was depending on access to atomic reserves for inconspicuous reasons.
In some cases it may be appropriate for them to use __GFP_HIGH.

The second key hazard is callers that assembled their own combination of
GFP flags instead of starting with something like GFP_KERNEL.  They may
now wish to specify __GFP_KSWAPD_RECLAIM.  It's almost certainly harmless
if it's missed in most cases as other activity will wake kswapd.

Signed-off-by: default avatarMel Gorman <mgorman@techsingularity.net>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Acked-by: default avatarMichal Hocko <mhocko@suse.com>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vitaly Wool <vitalywool@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      d0164adc
    • Sebastian Reichel's avatar
      Revert "ARM: dts: twl4030: Add iio properties for bci subnode" · 829a7da0
      Sebastian Reichel authored 
      

This reverts commit af19161a,
which breaks the omap3 device tree build due to a wrong reference.

I accidently queued this change via the power supply subsystem while
telling Marek at the same time, that it should go through Tony.
Following that I did miss Stephen's messages about the build failure in
linux-next and since he switched to merging an older snapshot nobody
else noticed the problem in my tree. I didn't notice myself, since I
did not build any device tree files assuming none have changed by me.

Signed-off-by: default avatarSebastian Reichel <sre@kernel.org>
Reported-by: default avatarFelipe Balbi <balbi@ti.com>
Tested-by: default avatarFelipe Balbi <balbi@ti.com>
Acked-by: default avatarFelipe Balbi <balbi@ti.com>
Tested-by: default avatarKevin Hilman <khilman@linaro.org>
Acked-by: default avatarTony Lindgren <tony@atomide.com>
      829a7da0
  25. Nov 06, 2015
    • Andrew Morton's avatar
      uaccess: reimplement probe_kernel_address() using probe_kernel_read() · 0ab32b6f
      Andrew Morton authored 
      

probe_kernel_address() is basically the same as the (later added)
probe_kernel_read().

The return value on EFAULT is a bit different: probe_kernel_address()
returns number-of-bytes-not-copied whereas probe_kernel_read() returns
-EFAULT.  All callers have been checked, none cared.

probe_kernel_read() can be overridden by the architecture whereas
probe_kernel_address() cannot.  parisc, blackfin and um do this, to insert
additional checking.  Hence this patch possibly fixes obscure bugs,
although there are only two probe_kernel_address() callsites outside
arch/.

My first attempt involved removing probe_kernel_address() entirely and
converting all callsites to use probe_kernel_read() directly, but that got
tiresome.

This patch shrinks mm/slab_common.o by 218 bytes.  For a single
probe_kernel_address() callsite.

Cc: Steven Miao <realmz6@gmail.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: "James E.J. Bottomley" <jejb@parisc-linux.org>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      0ab32b6f
  27. Nov 03, 2015
  29. Nov 02, 2015
  31. Oct 31, 2015
  33. Oct 29, 2015
  35. Oct 28, 2015
  37. Oct 27, 2015