The name_to_dev_t function has a comment block which lists the supported
syntaxes for the device name. Add a bullet for the <major>:<minor>
syntax, which is already supported in the code
Signed-off-by: Sebastian Capella <sebastian.capella@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The CONFIG_HPET_MMAP Kconfig option exposes the memory map of the HPET
registers to userspace. The Kconfig help points out that in some cases
this can be a security risk as some systems may erroneously configure the
map such that additional data is exposed to userspace.
This is a problem for distributions -- some users want the MMAP
functionality but it comes with a significant security risk. In an effort
to mitigate this risk, and due to the low number of users of the MMAP
functionality, I've introduced a kernel parameter, hpet_mmap_enable, that
is required in order to actually have the HPET MMAP exposed.
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Acked-by: Matt Wilson <msw@amazon.com>
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Tomas Winkler <tomas.winkler@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 0255d49184 ("mm: Account for a THP NUMA hinting update as one
PTE update") was added to account for the number of PTE updates when
marking pages prot_numa. task_numa_work was using the old return value
to track how much address space had been updated. Altering the return
value causes the scanner to do more work than it is configured or
documented to in a single unit of work.
This patch reverts that commit and accounts for the number of THP
updates separately in vmstat. It is up to the administrator to
interpret the pair of values correctly. This is a straight-forward
operation and likely to only be of interest when actively debugging NUMA
balancing problems.
The impact of this patch is that the NUMA PTE scanner will scan slower
when THP is enabled and workloads may converge slower as a result. On
the flip size system CPU usage should be lower than recent tests
reported. This is an illustrative example of a short single JVM specjbb
test
specjbb
3.12.0 3.12.0
vanilla acctupdates
TPut 1 26143.00 ( 0.00%) 25747.00 ( -1.51%)
TPut 7 185257.00 ( 0.00%) 183202.00 ( -1.11%)
TPut 13 329760.00 ( 0.00%) 346577.00 ( 5.10%)
TPut 19 442502.00 ( 0.00%) 460146.00 ( 3.99%)
TPut 25 540634.00 ( 0.00%) 549053.00 ( 1.56%)
TPut 31 512098.00 ( 0.00%) 519611.00 ( 1.47%)
TPut 37 461276.00 ( 0.00%) 474973.00 ( 2.97%)
TPut 43 403089.00 ( 0.00%) 414172.00 ( 2.75%)
3.12.0 3.12.0
vanillaacctupdates
User 5169.64 5184.14
System 100.45 80.02
Elapsed 252.75 251.85
Performance is similar but note the reduction in system CPU time. While
this showed a performance gain, it will not be universal but at least
it'll be behaving as documented. The vmstats are obviously different but
here is an obvious interpretation of them from mmtests.
3.12.0 3.12.0
vanillaacctupdates
NUMA page range updates 1408326 11043064
NUMA huge PMD updates 0 21040
NUMA PTE updates 1408326 291624
"NUMA page range updates" == nr_pte_updates and is the value returned to
the NUMA pte scanner. NUMA huge PMD updates were the number of THP
updates which in combination can be used to calculate how many ptes were
updated from userspace.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reported-by: Alex Thorlton <athorlton@sgi.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The same calculation is currently done in three differents places.
Factor that code so future changes has to be made at only one place.
[akpm@linux-foundation.org: uninline vm_commit_limit()]
Signed-off-by: Jerome Marchand <jmarchan@redhat.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Now dirty_background_ratio/dirty_ratio contains a percentage of total
avaiable memory, which contains free pages and reclaimable pages. The
number of these pages is not equal to the number of total system memory.
But they are described as a percentage of total system memory in
Documentation/sysctl/vm.txt. So we need to fix them to avoid
misunderstanding.
Signed-off-by: Zheng Liu <wenqing.lz@taobao.com>
Cc: Rob Landley <rob@landley.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The refcount routine was not fit the kernel get/put semantic exactly,
There were too many judgement statements on refcount and it could be
minus.
This patch does the following:
- move refcount judgement to zswap_entry_put() to hide resource free function.
- add a new function zswap_entry_find_get(), so that callers can use
easily in the following pattern:
zswap_entry_find_get
.../* do something */
zswap_entry_put
- to eliminate compile error, move some functions declaration
This patch is based on Minchan Kim <minchan@kernel.org> 's idea and suggestion.
Signed-off-by: Weijie Yang <weijie.yang@samsung.com>
Cc: Seth Jennings <sjennings@variantweb.net>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Bob Liu <bob.liu@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Consider the following scenario:
thread 0: reclaim entry x (get refcount, but not call zswap_get_swap_cache_page)
thread 1: call zswap_frontswap_invalidate_page to invalidate entry x.
finished, entry x and its zbud is not freed as its refcount != 0
now, the swap_map[x] = 0
thread 0: now call zswap_get_swap_cache_page
swapcache_prepare return -ENOENT because entry x is not used any more
zswap_get_swap_cache_page return ZSWAP_SWAPCACHE_NOMEM
zswap_writeback_entry do nothing except put refcount
Now, the memory of zswap_entry x and its zpage leak.
Modify:
- check the refcount in fail path, free memory if it is not referenced.
- use ZSWAP_SWAPCACHE_FAIL instead of ZSWAP_SWAPCACHE_NOMEM as the fail path
can be not only caused by nomem but also by invalidate.
Signed-off-by: Weijie Yang <weijie.yang@samsung.com>
Reviewed-by: Bob Liu <bob.liu@oracle.com>
Reviewed-by: Minchan Kim <minchan@kernel.org>
Acked-by: Seth Jennings <sjenning@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch fixes the problem that get_unmapped_area() can return illegal
address and result in failing mmap(2) etc.
In case that the address higher than PAGE_SIZE is set to
/proc/sys/vm/mmap_min_addr, the address lower than mmap_min_addr can be
returned by get_unmapped_area(), even if you do not pass any virtual
address hint (i.e. the second argument).
This is because the current get_unmapped_area() code does not take into
account mmap_min_addr.
This leads to two actual problems as follows:
1. mmap(2) can fail with EPERM on the process without CAP_SYS_RAWIO,
although any illegal parameter is not passed.
2. The bottom-up search path after the top-down search might not work in
arch_get_unmapped_area_topdown().
Note: The first and third chunk of my patch, which changes "len" check,
are for more precise check using mmap_min_addr, and not for solving the
above problem.
[How to reproduce]
--- test.c -------------------------------------------------
#include <stdio.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/errno.h>
int main(int argc, char *argv[])
{
void *ret = NULL, *last_map;
size_t pagesize = sysconf(_SC_PAGESIZE);
do {
last_map = ret;
ret = mmap(0, pagesize, PROT_NONE,
MAP_PRIVATE|MAP_ANONYMOUS, -1, 0);
// printf("ret=%p\n", ret);
} while (ret != MAP_FAILED);
if (errno != ENOMEM) {
printf("ERR: unexpected errno: %d (last map=%p)\n",
errno, last_map);
}
return 0;
}
---------------------------------------------------------------
$ gcc -m32 -o test test.c
$ sudo sysctl -w vm.mmap_min_addr=65536
vm.mmap_min_addr = 65536
$ ./test (run as non-priviledge user)
ERR: unexpected errno: 1 (last map=0x10000)
Signed-off-by: Akira Takeuchi <takeuchi.akr@jp.panasonic.com>
Signed-off-by: Kiyoshi Owada <owada.kiyoshi@jp.panasonic.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When __rmqueue_fallback() doesn't find a free block with the required size
it splits a larger page and puts the rest of the page onto the free list.
But it has one serious mistake. When putting back, __rmqueue_fallback()
always use start_migratetype if type is not CMA. However,
__rmqueue_fallback() is only called when all of the start_migratetype
queue is empty. That said, __rmqueue_fallback always puts back memory to
the wrong queue except try_to_steal_freepages() changed pageblock type
(i.e. requested size is smaller than half of page block). The end result
is that the antifragmentation framework increases fragmenation instead of
decreasing it.
Mel's original anti fragmentation does the right thing. But commit
47118af076 ("mm: mmzone: MIGRATE_CMA migration type added") broke it.
This patch restores sane and old behavior. It also removes an incorrect
comment which was introduced by commit fef903efcf ("mm/page_alloc.c:
restructure free-page stealing code and fix a bug").
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Nazarewicz <mina86@mina86.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In general, every tracepoint should be zero overhead if it is disabled.
However, trace_mm_page_alloc_extfrag() is one of exception. It evaluate
"new_type == start_migratetype" even if tracepoint is disabled.
However, the code can be moved into tracepoint's TP_fast_assign() and
TP_fast_assign exist exactly such purpose. This patch does it.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, set_pageblock_migratetype() screws up MIGRATE_CMA and
MIGRATE_ISOLATE if page_group_by_mobility_disabled is true. It rewrites
the argument to MIGRATE_UNMOVABLE and we lost these attribute.
The problem was introduced by commit 49255c619f ("page allocator: move
check for disabled anti-fragmentation out of fastpath"). So a 4 year
old issue may mean that nobody uses page_group_by_mobility_disabled.
But anyway, this patch fixes the problem.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The kernel's readahead algorithm sometimes interprets random read
accesses as sequential and triggers unnecessary data prefecthing from
storage device (impacting random read average latency).
In order to identify sequential cache read misses, the readahead
algorithm intends to check whether offset - previous offset == 1
(trivial sequential reads) or offset - previous offset == 0 (sequential
reads not aligned on page boundary):
if (offset - (ra->prev_pos >> PAGE_CACHE_SHIFT) <= 1UL)
The current offset is stored in the "offset" variable of type "pgoff_t"
(unsigned long), while previous offset is stored in "ra->prev_pos" of
type "loff_t" (long long). Therefore, operands of the if statement are
implicitly converted to type long long. Consequently, when previous
offset > current offset (which happens on random pattern), the if
condition is true and access is wrongly interpeted as sequential. An
unnecessary data prefetching is triggered, impacting the average random
read latency.
Storing the previous offset value in a "pgoff_t" variable (unsigned
long) fixes the sequential read detection logic.
Signed-off-by: Damien Ramonda <damien.ramonda@intel.com>
Reviewed-by: Fengguang Wu <fengguang.wu@intel.com>
Acked-by: Pierre Tardy <pierre.tardy@intel.com>
Acked-by: David Cohen <david.a.cohen@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It has been reported on very large machines that show_mem is taking almost
5 minutes to display information. This is a serious problem if there is
an OOM storm. The bulk of the cost is in show_mem doing a very expensive
PFN walk to give us the following information
Total RAM: Also available as totalram_pages
Highmem pages: Also available as totalhigh_pages
Reserved pages: Can be inferred from the zone structure
Shared pages: PFN walk required
Unshared pages: PFN walk required
Quick pages: Per-cpu walk required
Only the shared/unshared pages requires a full PFN walk but that
information is useless. It is also inaccurate as page pins of unshared
pages would be accounted for as shared. Even if the information was
accurate, I'm struggling to think how the shared/unshared information
could be useful for debugging OOM conditions. Maybe it was useful before
rmap existed when reclaiming shared pages was costly but it is less
relevant today.
The PFN walk could be optimised a bit but why bother as the information is
useless. This patch deletes the PFN walker and infers the total RAM,
highmem and reserved pages count from struct zone. It omits the
shared/unshared page usage on the grounds that it is useless. It also
corrects the reporting of HighMem as HighMem/MovableOnly as ZONE_MOVABLE
has similar problems to HighMem with respect to lowmem/highmem exhaustion.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
vmstat_cpuup_callback() is a CPU notifier callback, which marks N_CPU to a
node at CPU online event. However, it does not update this N_CPU info at
CPU offline event.
Changed vmstat_cpuup_callback() to clear N_CPU when the last CPU in the
node is put into offline, i.e. the node no longer has any online CPU.
Signed-off-by: Toshi Kani <toshi.kani@hp.com>
Acked-by: Christoph Lameter <cl@linux.com>
Reviewed-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Tested-by: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Eric Sandeen
Sebastian Capella
Andi Kleen
Michael Opdenacker
Greg Thelen
Prarit Bhargava
Mel Gorman
Jerome Marchand
Zheng Liu
Zhi Yong Wu
Weijie Yang
Qiang Huang
Akira Takeuchi
KOSAKI Motohiro
Damien Ramonda
Daeseok Youn
Toshi Kani