However the feature can be useful for other relatively slow or untrusted
BDIs like USB flash drives and DVD+RW. The patch adds a knob to enable
the feature:
echo 1 > /sys/class/bdi/X:Y/strictlimit
Being enabled, the feature enforces bdi max_ratio limit even if global
(10%) dirty limit is not reached. Of course, the effect is not visible
until /sys/class/bdi/X:Y/max_ratio is decreased to some reasonable value.
Signed-off-by: Maxim Patlasov <MPatlasov@parallels.com> Cc: Henrique de Moraes Holschuh <hmh@hmh.eng.br> Cc: Theodore Ts'o <tytso@mit.edu> Cc: "Artem S. Tashkinov" <t.artem@lycos.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Jan Kara <jack@suse.cz> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Fabian Frederick [Thu, 22 May 2014 00:54:45 +0000 (10:54 +1000)]
ufs: sb mutex merge + mutex_destroy
788257d6101d9 ("ufs: remove the BKL") replaced BKL with mutex protection
using functions lock_ufs, unlock_ufs and struct mutex 'mutex' in sb_info.
b6963327e052 ("ufs: drop lock/unlock super") removed lock/unlock super and
added struct mutex 's_lock' in sb_info.
Those 2 mutexes are generally locked/unlocked at the same time except in
allocation (balloc, ialloc).
This patch merges the 2 mutexes and propagates first commit solution. It
also adds mutex destruction before kfree during ufs_fill_super failure and
ufs_put_super.
[akpm@linux-foundation.org: avoid ifdefs, return -EROFS not -EINVAL] Signed-off-by: Fabian Frederick <fabf@skynet.be> Cc: Evgeniy Dushistov <dushistov@mail.ru> Cc: "Chen, Jet" <jet.chen@intel.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Levente Kurusa [Thu, 22 May 2014 00:54:45 +0000 (10:54 +1000)]
drivers/w1/w1_int.c: call put_device if device_register fails
Currently, memsetting and kfreeing the device is bad behaviour. The
device will have a reference count of 1 and hence can cause trouble
because it has kfree'd. Proper way to handle a failed device_register is
to call put_device right after it fails.
printk is meant to be used with an associated log level. There are some
instances of printk scattered around the mm code where the log level is
missing. Add a log level and adhere to suggestions by
scripts/checkpatch.pl by moving to the pr_* macros.
Also add the typical pr_fmt definition so that print statements can be
easily traced back to the modules where they occur, correlated one with
another, etc. This will require the removal of some (now redundant)
prefixes on a few print statements.
Signed-off-by: Mitchel Humpherys <mitchelh@codeaurora.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Josh Triplett [Thu, 22 May 2014 00:54:44 +0000 (10:54 +1000)]
MAINTAINERS: add linux-api for review of API/ABI changes
This makes it more likely that patch submitters will CC API/ABI changes to
the linux-api list, and tools like get_maintainer.pl will do so
automatically.
Signed-off-by: Josh Triplett <josh@joshtriplett.org> Acked-by: Steven Rostedt <rostedt@goodmis.org> Acked-by: Michael Kerrisk <mtk.man-pages@gmail.com> Cc: Joe Perches <joe@perches.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In case of error, V2 restored the previous number of segments but left
the BIO_SEG_FLAG set.
To avoid problems, after the page is removed from the bio vec,
V3 performs a recount of the segments in the error code path.
Signed-off-by: Maurizio Lombardi <mlombard@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Cc: Kent Overstreet <kmo@daterainc.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
bio: modify __bio_add_page() to accept pages that don't start a new segment
The original behaviour is to refuse to add a new page if the maximum
number of segments has been reached, regardless of the fact the page we
are going to add can be merged into the last segment or not.
Unfortunately, when the system runs under heavy memory fragmentation
conditions, a driver may try to add multiple pages to the last segment.
The original code won't accept them and EBUSY will be reported to
userspace.
This patch modifies the function so it refuses to add a page only in case
the latter starts a new segment and the maximum number of segments has
already been reached.
The bug can be easily reproduced with the st driver:
1) set CONFIG_SCSI_MPT2SAS_MAX_SGE or CONFIG_SCSI_MPT3SAS_MAX_SGE to 16
2) modprobe st buffer_kbs=1024
3) #dd if=/dev/zero of=/dev/st0 bs=1M count=10
dd: error writing `/dev/st0': Device or resource busy
Signed-off-by: Maurizio Lombardi <mlombard@redhat.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Christoph Hellwig <hch@lst.de> Cc: Kent Overstreet <kmo@daterainc.com> Cc: Jens Axboe <axboe@kernel.dk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Aaron Tomlin <atomlin@redhat.com> Cc: Don Zickus <dzickus@redhat.com> Cc: David S. Miller <davem@davemloft.net> Cc: Mateusz Guzik <mguzik@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Aaron Tomlin [Thu, 22 May 2014 00:54:42 +0000 (10:54 +1000)]
nmi: provide the option to issue an NMI back trace to every cpu but current
Sometimes it is preferred not to use the trigger_all_cpu_backtrace()
routine when one wants to avoid capturing a back trace for current. For
instance if one was previously captured recently.
This patch provides a new routine namely
trigger_allbutself_cpu_backtrace() which offers the flexibility to issue
an NMI to every cpu but current and capture a back trace accordingly.
Patch x86 and sparc to support new routine.
[dzickus@redhat.com: add stub in #else clause]
[dzickus@redhat.com: don't print message in single processor case, wrap with get/put_cpu based on Oleg's suggestion] Signed-off-by: Aaron Tomlin <atomlin@redhat.com> Signed-off-by: Don Zickus <dzickus@redhat.com> Acked-by: David S. Miller <davem@davemloft.net> Cc: Mateusz Guzik <mguzik@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Namjae Jeon [Thu, 22 May 2014 00:54:41 +0000 (10:54 +1000)]
fat: fallback to buffered write in case of fallocated region on direct IO
For normal cases of direct IO write, trying to seek to location greater
than file size, makes it fall back to buffered write to fill that region.
Similarly, in case for write in Fallocated region, make it fall to
buffered write.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com> Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Namjae Jeon [Thu, 22 May 2014 00:54:41 +0000 (10:54 +1000)]
fat: zero out seek range on _fat_get_block
For normal buffered write operations, normally if we try to write to an
offset > than file size, it does a cont_expand_zero till that offset.
Now, in case of fallocated regions, since the blocks are already
allocated. So, make it zero out that buffers for those blocks till the
seek'ed offset.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com> Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Namjae Jeon [Thu, 22 May 2014 00:54:40 +0000 (10:54 +1000)]
fat: add fat_fallocate operation
Implement preallocation via the fallocate syscall on VFAT partitions.
This patch is based on an earlier patch of the same name which had some
issues detailed below and did not get accepted. Refer
https://lkml.org/lkml/2007/12/22/130.
a) The preallocated space was not persistent when the
FALLOC_FL_KEEP_SIZE flag was set. It will deallocate cluster at evict
time.
b) There was no need to zero out the clusters when the flag was set
Instead of doing an expanding truncate, just allocate clusters and add
them to the fat chain. This reduces preallocation time.
Compatibility with windows:
There are no issues when FALLOC_FL_KEEP_SIZE is not set because it just
does an expanding truncate. Thus reading from the preallocated area on
windows returns null until data is written to it.
When a file with preallocated area using the FALLOC_FL_KEEP_SIZE was
written to on windows, the windows driver freed-up the preallocated
clusters and allocated new clusters for the new data. The freed up
clusters gets reflected in the free space available for the partition
which can be seen from the Volume properties.
The windows chkdsk tool also does not report any errors on a disk
containing files with preallocated space.
And there is also no issue using linux fat fsck. because discard
preallocated clusters at repair time.
Signed-off-by: Namjae Jeon <namjae.jeon@samsung.com> Signed-off-by: Amit Sahrawat <a.sahrawat@samsung.com> Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Michal Hocko [Thu, 22 May 2014 00:54:40 +0000 (10:54 +1000)]
memcg: deprecate memory.force_empty knob
force_empty has been introduced primarily to drop memory before it gets
reparented on the group removal. This alone doesn't sound fully justified
because reparented pages which are not in use can be reclaimed also later
when there is a memory pressure on the parent level.
Mark the knob CFTYPE_INSANE which tells the cgroup core that it shouldn't
create the knob with the experimental sane_behavior. Other users will get
informed about the deprecation and asked to tell us more because I do not
expect most users will use sane_behavior cgroups mode very soon.
Anyway I expect that most users will be simply cgroup remove handlers
which do that since ever without having any good reason for it.
If somebody really cares because reparented pages, which would be dropped
otherwise, push out more important ones then we should fix the reparenting
code and put pages to the tail.
Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Greg Thelen <gthelen@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: replace remap_file_pages() syscall with emulation
remap_file_pages(2) was invented to be able efficiently map parts of huge
file into limited 32-bit virtual address space such as in database
workloads.
Nonlinear mappings are pain to support and it seems there's no legitimate
use-cases nowadays since 64-bit systems are widely available.
Let's drop it and get rid of all these special-cased code.
The patch replaces the syscall with emulation which creates new VMA on
each remap_file_pages(), unless they it can be merged with an adjacent
one.
I didn't find *any* real code that uses remap_file_pages(2) to test
emulation impact on. I've checked Debian code search and source of all
packages in ALT Linux. No real users: libc wrappers, mentions in strace,
gdb, valgrind and this kind of stuff.
There are few basic tests in LTP for the syscall. They work just fine
with emulation.
To test performance impact, I've written small test case which demonstrate
pretty much worst case scenario: map 4G shmfs file, write to begin of
every page pgoff of the page, remap pages in reverse order, read every
page.
The test creates 1 million of VMAs if emulation is in use, so I had to set
vm.max_map_count to 1100000 to avoid -ENOMEM.
The remap_file_pages() system call is used to create a nonlinear mapping,
that is, a mapping in which the pages of the file are mapped into a
nonsequential order in memory. The advantage of using remap_file_pages()
over using repeated calls to mmap(2) is that the former approach does not
require the kernel to create additional VMA (Virtual Memory Area) data
structures.
Supporting of nonlinear mapping requires significant amount of non-trivial
code in kernel virtual memory subsystem including hot paths. Also to get
nonlinear mapping work kernel need a way to distinguish normal page table
entries from entries with file offset (pte_file). Kernel reserves flag in
PTE for this purpose. PTE flags are scarce resource especially on some
CPU architectures. It would be nice to free up the flag for other usage.
Fortunately, there are not many users of remap_file_pages() in the wild.
It's only known that one enterprise RDBMS implementation uses the syscall
on 32-bit systems to map files bigger than can linearly fit into 32-bit
virtual address space. This use-case is not critical anymore since 64-bit
systems are widely available.
The plan is to deprecate the syscall and replace it with an emulation.
The emulation will create new VMAs instead of nonlinear mappings. It's
going to work slower for rare users of remap_file_pages() but ABI is
preserved.
One side effect of emulation (apart from performance) is that user can hit
vm.max_map_count limit more easily due to additional VMAs. See comment
for DEFAULT_MAX_MAP_COUNT for more details on the limit.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: Dave Jones <davej@redhat.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Armin Rigo <arigo@tunes.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Jianyu Zhan [Thu, 22 May 2014 00:54:38 +0000 (10:54 +1000)]
mm: memcontrol: clean up memcg zoneinfo lookup
Memcg zoneinfo lookup sites have either the page, the zone, or the node id
and zone index, but sites that only have the zone have to look up the node
id and zone index themselves, whereas sites that already have those two
integers use a function for a simple pointer chase.
Provide mem_cgroup_zone_zoneinfo() that takes a zone pointer and let sites
that already have node id and zone index - all for each node, for each
zone iterators - use &memcg->nodeinfo[nid]->zoneinfo[zid].
Rename page_cgroup_zoneinfo() to mem_cgroup_page_zoneinfo() to match.
Signed-off-by: Jianyu Zhan <nasa4836@gmail.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Catalin Marinas [Thu, 22 May 2014 00:54:37 +0000 (10:54 +1000)]
mm/memblock.c: call kmemleak directly from memblock_(alloc|free)
Kmemleak could ignore memory blocks allocated via memblock_alloc() leading
to false positives during scanning. This patch adds the corresponding
callbacks and removes kmemleak_free_* calls in mm/nobootmem.c to avoid
duplication. The kmemleak_alloc() in mm/nobootmem.c is kept since
__alloc_memory_core_early() does not use memblock_alloc() directly.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Catalin Marinas [Thu, 22 May 2014 00:54:37 +0000 (10:54 +1000)]
mm/mempool.c: update the kmemleak stack trace for mempool allocations
When mempool_alloc() returns an existing pool object, kmemleak_alloc() is
no longer called and the stack trace corresponds to the original object
allocation. This patch updates the kmemleak allocation stack trace for
such objects to make it more useful for debugging.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Catalin Marinas [Thu, 22 May 2014 00:54:37 +0000 (10:54 +1000)]
lib/radix-tree.c: update the kmemleak stack trace for radix tree allocations
Since radix_tree_preload() stack trace is not always useful for debugging
an actual radix tree memory leak, this patch updates the kmemleak
allocation stack trace in the radix_tree_node_alloc() function.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Catalin Marinas [Thu, 22 May 2014 00:54:37 +0000 (10:54 +1000)]
mm: introduce kmemleak_update_trace()
The memory allocation stack trace is not always useful for debugging a
memory leak (e.g. radix_tree_preload). This function, when called,
updates the stack trace for an already allocated object.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Michal Hocko [Thu, 22 May 2014 00:54:36 +0000 (10:54 +1000)]
vmscan: memcg: always use swappiness of the reclaimed memcg
Memory reclaim always uses swappiness of the reclaim target memcg (origin
of the memory pressure) or vm_swappiness for global memory reclaim. This
behavior was consistent (except for difference between global and hard
limit reclaim) because swappiness was enforced to be consistent within
each memcg hierarchy.
After "mm: memcontrol: remove hierarchy restrictions for swappiness and
oom_control" each memcg can have its own swappiness independent of
hierarchical parents, though, so the consistency guarantee is gone. This
can lead to an unexpected behavior. Say that a group is explicitly
configured to not swapout by memory.swappiness=0 but its memory gets
swapped out anyway when the memory pressure comes from its parent with a
It is also unexpected that the knob is meaningless without setting the
hard limit which would trigger the reclaim and enforce the swappiness.
There are setups where the hard limit is configured higher in the
hierarchy by an administrator and children groups are under control of
somebody else who is interested in the swapout behavior but not
necessarily about the memory limit.
From a semantic point of view swappiness is an attribute defining anon vs.
file proportional scanning of LRU which is memcg specific (unlike charges
which are propagated up the hierarchy) so it should be applied to the
particular memcg's LRU regardless where the memory pressure comes from.
This patch removes vmscan_swappiness() and stores the swappiness into the
scan_control structure. mem_cgroup_swappiness is then used to provide the
correct value before shrink_lruvec is called. The global vm_swappiness is
used for the root memcg.
Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Tejun Heo <tj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Michal Hocko [Thu, 22 May 2014 00:54:36 +0000 (10:54 +1000)]
vmscan: memcg: check whether the low limit should be ignored
Low-limit (aka guarantee) is ignored when there is no group scanned during
the first round of __shink_zone. This approach doesn't work when multiple
reclaimers race and reclaim the same hierarchy (e.g. kswapd vs. direct
reclaim or multiple tasks hitting the hard limit) because memcg iterator
makes sure that multiple reclaimers are interleaved in the hierarchy.
This means that some reclaimers can see 0 scanned groups although there
are groups which are above the low-limit and they were reclaimed on behalf
of other reclaimers. This leads to a premature low-limit break.
This patch adds mem_cgroup_all_within_guarantee() which will check whether
all the groups in the reclaimed hierarchy are within their low limit and
shrink_zone will allow the fallback reclaim only when that is true. This
alone is still not sufficient however because it would lead to another
problem. If a reclaimer constantly fails to scan anything because it sees
only groups within their guarantees while others do the reclaim then the
reclaim priority would drop down very quickly. shrink_zone has to be
careful to preserve scan at least one group semantic so __shrink_zone has
to be retried until at least one group is scanned.
Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Greg Thelen <gthelen@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Roman Gushchin <klamm@yandex-team.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Michal Hocko [Thu, 22 May 2014 00:54:35 +0000 (10:54 +1000)]
memcg: allow setting low_limit
Export memory.low_limit_in_bytes knob with the same rules as the hard
limit represented by limit_in_bytes knob (e.g. no limit to be set for the
root cgroup). There is no memsw alternative for low_limit_in_bytes
because the primary motivation behind this limit is to protect the working
set of the group and so considering swap doesn't make much sense. There
is also no kmem variant exported because we do not have any easy way to
protect kernel allocations now.
Please note that the low limit might exceed the hard limit which basically
means that the group is not reclaimable if there is other reclaim target
in the hierarchy under pressure.
Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Greg Thelen <gthelen@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Roman Gushchin <klamm@yandex-team.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Michal Hocko [Thu, 22 May 2014 00:54:34 +0000 (10:54 +1000)]
memcg, mm: introduce lowlimit reclaim
Previous discussions have shown that soft limits cannot be reformed
(http://lwn.net/Articles/555249/). This series introduces an alternative
approach for protecting memory allocated to processes executing within a
memory cgroup controller. It is based on a new tunable that was discussed
with Johannes and Tejun held during the kernel summit 2013 and at LSF
2014.
This patchset introduces such low limit that is functionally similar to a
minimum guarantee. Memcgs which are under their lowlimit are not
considered eligible for the reclaim (both global and hardlimit) unless all
groups under the reclaimed hierarchy are below the low limit when all of
them are considered eligible.
The previous version of the patchset posted as a RFC
(http://marc.info/?l=linux-mm&m=138677140628677&w=2) suggested a hard
guarantee without any fallback. More discussions led me to reconsidering
the default behavior and come up a more relaxed one. The hard requirement
can be added later based on a use case which really requires. It would be
controlled by memory.reclaim_flags knob which would specify whether to OOM
or fallback (default) when all groups are bellow low limit.
The default value of the limit is 0 so all groups are eligible by default
and an interested party has to explicitly set the limit.
The primary use case is to protect an amount of memory allocated to a
workload without it being reclaimed by an unrelated activity. In some
cases this requirement can be fulfilled by mlock but it is not suitable
for many loads and generally requires application awareness. Such
application awareness can be complex. It effectively forbids the use of
memory overcommit as the application must explicitly manage memory
residency.
With the low limit, such workloads can be placed in a memcg with a low
limit that protects the estimated working set.
The hierarchical behavior of the lowlimit is described in the first patch.
The second patch allows setting the lowlimit. The last 2 patches clarify
documentation about the memcg reclaim in gereneral (3rd patch) and low
limit (4th patch).
This patch (of 5)
This patch introduces low limit reclaim. The low_limit acts as a reclaim
protection because groups which are under their low_limit are considered
ineligible for reclaim. While hardlimit protects from using more memory
than allowed lowlimit protects from getting below memory assigned to the
group due to external memory pressure.
More precisely a group is considered eligible for the reclaim under a
specific hierarchy represented by its root only if the group is above its
low limit and the same applies to all parents up the hierarchy to the
root. Nevertheless the limit still might be ignored if all groups under
the reclaimed hierarchy are under their low limits. This will prevent
from OOM rather than protecting the memory.
Consider the following hierarchy with memory pressure coming from the
group A (hard limit reclaim - l-low_limit_in_bytes, u-usage_in_bytes,
h-limit_in_bytes):
root_mem_cgroup
.
_____/
/
A (l = 80 u=90 h=90)
/
/ \_________
/ \
B (l=0 u=50) C (l=50 u=40)
\
D (l=0 u=30)
A and B are reclaimable but C and D are not (D is protected by C).
The low_limit is 0 by default so every group is eligible. This patch
doesn't provide a way to set the limit yet although the core
infrastructure is there already.
Signed-off-by: Michal Hocko <mhocko@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Greg Thelen <gthelen@google.com> Cc: Michel Lespinasse <walken@google.com> Cc: Tejun Heo <tj@kernel.org> Cc: Hugh Dickins <hughd@google.com> Cc: Roman Gushchin <klamm@yandex-team.ru> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Rik van Riel [Thu, 22 May 2014 00:54:34 +0000 (10:54 +1000)]
sysrq,rcu: suppress RCU stall warnings while sysrq runs
Some sysrq handlers can run for a long time, because they dump a lot of
data onto a serial console. Having RCU stall warnings pop up in the
middle of them only makes the problem worse.
This patch temporarily disables RCU stall warnings while a sysrq request
is handled.
Signed-off-by: Rik van Riel <riel@redhat.com> Suggested-by: Paul McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Madper Xie <cxie@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Richard Weinberger <richard@nod.at> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Rik van Riel [Thu, 22 May 2014 00:54:34 +0000 (10:54 +1000)]
sysrq: rcu-ify __handle_sysrq
Echoing values into /proc/sysrq-trigger seems to be a popular way to get
information out of the kernel. However, dumping information about
thousands of processes, or hundreds of CPUs to serial console can result
in IRQs being blocked for minutes, resulting in various kinds of cascade
failures.
The most common failure is due to interrupts being blocked for a very long
time. This can lead to things like failed IO requests, and other things
the system cannot easily recover from.
This problem is easily fixable by making __handle_sysrq use RCU instead of
spin_lock_irqsave.
This leaves the warning that RCU grace periods have not elapsed for a long
time, but the system will come back from that automatically.
It also leaves sysrq-from-irq-context when the sysrq keys are pressed, but
that is probably desired since people want that to work in situations
where the system is already hosed.
The callers of register_sysrq_key and unregister_sysrq_key appear to be
capable of sleeping.
Signed-off-by: Rik van Riel <riel@redhat.com> Reported-by: Madper Xie <cxie@redhat.com> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Richard Weinberger <richard@nod.at> Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Fabian Frederick [Thu, 22 May 2014 00:54:33 +0000 (10:54 +1000)]
kernel/kprobes.c: convert printk to pr_foo()
Also fixes some checkpatch warnings
-Static initialization
-Lines over 80 characters
Signed-off-by: Fabian Frederick <fabf@skynet.be> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Davidlohr Bueso [Thu, 22 May 2014 00:54:32 +0000 (10:54 +1000)]
rwsem: Support optimistic spinning
We have reached the point where our mutexes are quite fine tuned for a
number of situations. This includes the use of heuristics and optimistic
spinning, based on MCS locking techniques.
Exclusive ownership of read-write semaphores are, conceptually, just about
the same as mutexes, making them close cousins. To this end we need to
make them both perform similarly, and right now, rwsems are simply not up
to it. This was discovered by both reverting commit 4fc3f1d6 (mm/rmap,
migration: Make rmap_walk_anon() and try_to_unmap_anon() more scalable)
and similarly, converting some other mutexes (ie: i_mmap_mutex) to rwsems.
This creates a situation where users have to choose between a rwsem and
mutex taking into account this important performance difference.
Specifically, biggest difference between both locks is when we fail to
acquire a mutex in the fastpath, optimistic spinning comes in to play and
we can avoid a large amount of unnecessary sleeping and overhead of moving
tasks in and out of wait queue. Rwsems do not have such logic.
This patch, based on the work from Tim Chen and I, adds support for
write-side optimistic spinning when the lock is contended. It also
includes support for the recently added cancelable MCS locking for
adaptive spinning. Note that is is only applicable to the xadd method,
and the spinlock rwsem variant remains intact.
Allowing optimistic spinning before putting the writer on the wait queue
reduces wait queue contention and provided greater chance for the rwsem to
get acquired. With these changes, rwsem is on par with mutex. The
performance benefits can be seen on a number of workloads. For instance,
on a 8 socket, 80 core 64bit Westmere box, aim7 shows the following
improvements in throughput:
There was also improvement on smaller systems, such as a quad-core x86-64
laptop running a 30Gb PostgreSQL (pgbench) workload for up to +60% in
throughput for over 50 clients. Additionally, benefits were also noticed
in exim (mail server) workloads. When comparing against regular
non-blocking rw locks ([q]rwlock_t), this change proves that it can
outperform them, for instance when studying the popular anon-vma lock:
kernel/watchdog.c: In function `watchdog_timer_fn':
kernel/watchdog.c:368:4: warning: `smp_mb__after_clear_bit' is deprecated (declared at include/linux/bitops.h:48) [-Wdeprecated-declarations]
smp_mb__after_clear_bit();
That code was introduced in commit 90e6b763ca8a5eb739e59489f42d45e13431d157
("kernel/watchdog.c: print traces for all cpus on lockup detection") and then
merged with another branch containing commit febdbfe8a91ce0d11939d4940b592eb0dba8d663 ("arch: Prepare for
smp_mb__{before,after}_atomic()") which deprecates the
smp_mb__after_clear_bit() call in favour of smp_mb__after_atomic().
Signed-off-by: Jan Moskyto Matejka <mq@suse.cz> Acked-by: Aaron Tomlin <atomlin@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Aaron Tomlin <atomlin@redhat.com> Cc: David S. Miller <davem@davemloft.net> Cc: Don Zickus <dzickus@redhat.com> Cc: Mateusz Guzik <mguzik@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Aaron Tomlin [Thu, 22 May 2014 00:54:31 +0000 (10:54 +1000)]
kernel/watchdog.c: print traces for all cpus on lockup detection
A 'softlockup' is defined as a bug that causes the kernel to loop in
kernel mode for more than a predefined period to time, without giving
other tasks a chance to run.
Currently, upon detection of this condition by the per-cpu watchdog task,
debug information (including a stack trace) is sent to the system log.
On some occasions, we have observed that the "victim" rather than the
actual "culprit" (i.e. the owner/holder of the contended resource) is
reported to the user. Often this information has proven to be
insufficient to assist debugging efforts.
To avoid loss of useful debug information, for architectures which support
NMI, this patch makes it possible to improve soft lockup reporting. This
is accomplished by issuing an NMI to each cpu to obtain a stack trace.
If NMI is not supported we just revert back to the old method. A sysctl
and boot-time parameter is available to toggle this feature.
[dzickus@redhat.com: add CONFIG_SMP in certain areas] Signed-off-by: Aaron Tomlin <atomlin@redhat.com> Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: David S. Miller <davem@davemloft.net> Cc: Mateusz Guzik <mguzik@redhat.com> Cc: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Davidlohr Bueso [Thu, 22 May 2014 00:54:30 +0000 (10:54 +1000)]
blackfin/ptrace: call find_vma with the mmap_sem held
Performing vma lookups without taking the mm->mmap_sem is asking for
trouble. While doing the search, the vma in question can be modified or
even removed before returning to the caller. Take the lock (shared) in
order to avoid races while iterating through the vmacache and/or rbtree.
Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Cc: Steven Miao <realmz6@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
rtc: s5m: consolidate two device type switch statements
In probe the configuration of driver for different chipsets was done in
two switch (pdata->device_type) statements. Consolidate them into one
switch statement to increase code readability.
Additionally check the return value of regmap_irq_get_virq and exit probe
on error.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> Cc: Kyungmin Park <kyungmin.park@samsung.com> Cc: Lee Jones <lee.jones@linaro.org> Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: Sangbeom Kim <sbkim73@samsung.com> Cc: Samuel Ortiz <sameo@linux.intel.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add support for S2MPS14 to the rtc-s5m driver. Differences in S2MPS14
(in comparison to S5M8767):
- Layout of registers;
- Lack of century support for time and alarms (7 registers used for
storing time/alarm);
- Two buffer control registers: WUDR and RUDR;
- No register for enabling writing time;
- RTC interrupts are reported in main PMIC I2C device;
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> Cc: Kyungmin Park <kyungmin.park@samsung.com> Cc: Lee Jones <lee.jones@linaro.org> Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: Sangbeom Kim <sbkim73@samsung.com> Cc: Samuel Ortiz <sameo@linux.intel.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Prepare for adding support for S2MPS14 RTC device to the
rtc-s5m driver:
1. Add a map of registers used by the driver which differ between
the chipsets (S5M876X and S2MPS14).
2. Move code of checking for alarm pending to separate function.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> Cc: Kyungmin Park <kyungmin.park@samsung.com> Cc: Lee Jones <lee.jones@linaro.org> Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: Sangbeom Kim <sbkim73@samsung.com> Cc: Samuel Ortiz <sameo@linux.intel.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Set the time needed for updating alarm and time registers to 0.45 ms.
The default is 7.32 ms which is too long and leads to warnings when
setting alarm or time:
s5m-rtc: waiting for UDR update, reached max number of retries
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> Cc: Kyungmin Park <kyungmin.park@samsung.com> Cc: Lee Jones <lee.jones@linaro.org> Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: Sangbeom Kim <sbkim73@samsung.com> Cc: Samuel Ortiz <sameo@linux.intel.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
rtc: s5m: remove undocumented time init on first boot
Remove the code for initializing time if this is first boot.
The code for detecting first boot uses undocumented field RTC_TCON in
RTC_UDR_CON register. According to S5M8767's datasheet this field is
reserved. On S2MPS14 it is not documented at all. On device first boot
the registers will be initialized with reset value (2000-01-01 00:00:00).
The code might work on S5M8763 but still this does not look like a task
for RTC driver.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> Cc: Kyungmin Park <kyungmin.park@samsung.com> Cc: Lee Jones <lee.jones@linaro.org> Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: Sangbeom Kim <sbkim73@samsung.com> Cc: Samuel Ortiz <sameo@linux.intel.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Prepare for adding support for S2MPS14 RTC device to the rtc-s5m driver:
1. Rename SEC* symbols to S5M.
2. Add S5M prefix to some of defines which are different between S5M876X
and S2MPS14.
This is only a rename-like patch, new code is not added.
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> Acked-by: Lee Jones <lee.jones@linaro.org> Cc: Kyungmin Park <kyungmin.park@samsung.com> Cc: Alessandro Zummo <a.zummo@towertech.it> Cc: Sangbeom Kim <sbkim73@samsung.com> Cc: Samuel Ortiz <sameo@linux.intel.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Andrew Morton [Thu, 22 May 2014 00:54:24 +0000 (10:54 +1000)]
mm/page_io.c: work around gcc bug
gcc-4.4.4 (at least) screws up this initialization.
mm/page_io.c: In function '__swap_writepage':
mm/page_io.c:277: error: unknown field 'bvec' specified in initializer
mm/page_io.c:278: warning: excess elements in struct initializer
mm/page_io.c:278: warning: (near initialization for 'from')
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