mm: micro-optimise slab to avoid a function call

Getting and putting objects in SLAB currently requires a function call but
the bulk of the work is related to PFMEMALLOC reserves which are only
consumed when network-backed storage is critical.  Use an inline function
to determine if the function call is required.

Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: David Miller <davem@davemloft.net>
Cc: Neil Brown <neilb@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Christie <michaelc@cs.wisc.edu>
Cc: Eric B Munson <emunson@mgebm.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Sebastian Andrzej Siewior <sebastian@breakpoint.cc>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
slab: do not call compound_head() in page_get_cache()

page_get_cache() does not need to call compound_head(), as its unique
caller virt_to_slab() already makes sure to return a head page.

Additionally, removing the compound_head() call makes page_get_cache()
consistent with page_get_slab().

Signed-off-by: Michel Lespinasse <walken@google.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
mm, slab: remove page_get_cache

page_get_cache() isn't called from anything, so remove it.

Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
mm, slab: lock the correct nodelist after reenabling irqs

cache_grow() can reenable irqs so the cpu (and node) can change, so ensure
that we take list_lock on the correct nodelist.

This fixes an issue with commit 072bb0aa5e06 ("mm: sl[au]b: add
knowledge of PFMEMALLOC reserve pages") where list_lock for the wrong
node was taken after growing the cache.

Reported-and-tested-by: Haggai Eran <haggaie@mellanox.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: Fix build warning in kmem_cache_create()

The label oops is used in CONFIG_DEBUG_VM ifdef block and is defined
outside ifdef CONFIG_DEBUG_VM block. This results in the following
build warning when built with CONFIG_DEBUG_VM disabled. Fix to move
label oops definition to inside a CONFIG_DEBUG_VM block.

mm/slab_common.c: In function ‘kmem_cache_create’:
mm/slab_common.c:101:1: warning: label ‘oops’ defined but not used
[-Wunused-label]

Signed-off-by: Shuah Khan <shuah.khan@hp.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Paul Reioux <reioux@gmail.com>

Conflicts:
	mm/slab_common.c
mm/slab_common.c: cleanup

Eliminate an ifdef and a label by moving all the CONFIG_DEBUG_VM checking
inside the locked region.

Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Revert "mm/slab_common.c: cleanup"

This reverts commit 455ce9eb1cfa083da0def023094190aeb133855a. Andrew
sent a better version.

Signed-off-by: Pekka Enberg <penberg@kernel.org>
mm/slab: restructure kmem_cache_create() debug checks

kmem_cache_create() does cache integrity checks when CONFIG_DEBUG_VM is
defined.  These checks interspersed with the regular code path has lead
to compile time warnings when compiled without CONFIG_DEBUG_VM defined.
Restructuring the code to move the integrity checks in to a new function
would eliminate the current compile warning problem and also will allow
for future changes to the debug only code to evolve without introducing
new warnings in the regular path.

This restructuring work is based on the discussion in the following
thread:

https://lkml.org/lkml/2012/7/13/424

[akpm@linux-foundation.org: fix build, cleanup]
Signed-off-by: Shuah Khan <shuah.khan@hp.com>
Acked-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
mm/slab_common: Improve error handling in kmem_cache_create

Instead of using s == NULL use an errorcode. This allows much more
detailed diagnostics as to what went wrong. As we add more functionality
from the slab allocators to the common kmem_cache_create() function we will
also add more error conditions.

Print the error code during the panic as well as in a warning if the module
can handle failure. The API for kmem_cache_create() currently does not allow
the returning of an error code. Return NULL but log the cause of the problem
in the syslog.

Reviewed-by: Glauber Costa <glommer@parallels.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
mm/sl[aou]b: Move list_add() to slab_common.c

Move the code to append the new kmem_cache to the list of slab caches to
the kmem_cache_create code in the shared code.

This is possible now since the acquisition of the mutex was moved into
kmem_cache_create().

Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
mm/sl[aou]b: Use "kmem_cache" name for slab cache with kmem_cache struct

Make all allocators use the "kmem_cache" slabname for the "kmem_cache"
structure.

Reviewed-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
mm/sl[aou]b: Extract a common function for kmem_cache_destroy

kmem_cache_destroy does basically the same in all allocators.

Extract common code which is easy since we already have common mutex
handling.

Reviewed-by: Glauber Costa <glommer@parallels.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
mm/sl[aou]b: Move freeing of kmem_cache structure to common code

The freeing action is basically the same in all slab allocators.
Move to the common kmem_cache_destroy() function.

Reviewed-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
mm/sl[aou]b: Get rid of __kmem_cache_destroy

What is done there can be done in __kmem_cache_shutdown.

This affects RCU handling somewhat. On rcu free all slab allocators do
not refer to other management structures than the kmem_cache structure.
Therefore these other structures can be freed before the rcu deferred
free to the page allocator occurs.

Reviewed-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
mm/sl[aou]b: Move duping of slab name to slab_common.c

Duping of the slabname has to be done by each slab. Moving this code to
slab_common avoids duplicate implementations.

With this patch we have common string handling for all slab allocators.
Strings passed to kmem_cache_create() are copied internally. Subsystems
can create temporary strings to create slab caches.

Slabs allocated in early states of bootstrap will never be freed (and
those can never be freed since they are essential to slab allocator
operations).  During bootstrap we therefore do not have to worry about
duping names.

Reviewed-by: Glauber Costa <glommer@parallels.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
mm/sl[aou]b: Do slab aliasing call from common code

The slab aliasing logic causes some strange contortions in slub. So add
a call to deal with aliases to slab_common.c but disable it for other
slab allocators by providng stubs that fail to create aliases.

Full general support for aliases will require additional cleanup passes
and more standardization of fields in kmem_cache.

Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
mm/sl[aou]b: Move sysfs_slab_add to common

Simplify locking by moving the slab_add_sysfs after all locks have been
dropped. Eases the upcoming move to provide sysfs support for all
allocators.

Reviewed-by: Glauber Costa <glommer@parallels.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>