The zone allocation batches can easily underflow due to higher-order
allocations or spills to remote nodes. On SMP that's fine, because
underflows are expected from concurrency and dealt with by returning 0.
But on UP, zone_page_state will just return a wrapped unsigned long,
which will get past the <= 0 check and then consider the zone eligible
until its watermarks are hit.
Commit 3a025760fc ("mm: page_alloc: spill to remote nodes before
waking kswapd") already made the counter-resetting use
atomic_long_read() to accomodate underflows from remote spills, but it
didn't go all the way with it.
Make it clear that these batches are expected to go negative regardless
of concurrency, and use atomic_long_read() everywhere.
Fixes: 81c0a2bb51 ("mm: page_alloc: fair zone allocator policy")
Reported-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Leon Romanovsky <leon@leon.nu>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: <stable@vger.kernel.org> [3.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The cgroup iterators yield css objects that have not yet gone through
css_online(), but they are not complete memcgs at this point and so the
memcg iterators should not return them. Commit d8ad305597 ("mm/memcg:
iteration skip memcgs not yet fully initialized") set out to implement
exactly this, but it uses CSS_ONLINE, a cgroup-internal flag that does
not meet the ordering requirements for memcg, and so the iterator may
skip over initialized groups, or return partially initialized memcgs.
The cgroup core can not reasonably provide a clear answer on whether the
object around the css has been fully initialized, as that depends on
controller-specific locking and lifetime rules. Thus, introduce a
memcg-specific flag that is set after the memcg has been initialized in
css_online(), and read before mem_cgroup_iter() callers access the memcg
members.
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org> [3.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch reverts 1ba6e0b50b ("mm: numa: split_huge_page: transfer the
NUMA type from the pmd to the pte"). If a huge page is being split due
a protection change and the tail will be in a PROT_NONE vma then NUMA
hinting PTEs are temporarily created in the protected VMA.
VM_RW|VM_PROTNONE
|-----------------|
^
split here
In the specific case above, it should get fixed up by change_pte_range()
but there is a window of opportunity for weirdness to happen. Similarly,
if a huge page is shrunk and split during a protection update but before
pmd_numa is cleared then a pte_numa can be left behind.
Instead of adding complexity trying to deal with the case, this patch
will not mark PTEs NUMA when splitting a huge page. NUMA hinting faults
will not be triggered which is marginal in comparison to the complexity
in dealing with the corner cases during THP split.
Cc: stable@vger.kernel.org
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A migration entry is marked as write if pte_write was true at the time the
entry was created. The VMA protections are not double checked when migration
entries are being removed as mprotect marks write-migration-entries as
read. It means that potentially we take a spurious fault to mark PTEs write
again but it's straight-forward. However, there is a race between write
migrations being marked read and migrations finishing. This potentially
allows a PTE to be write that should have been read. Close this race by
double checking the VMA permissions using maybe_mkwrite when migration
completes.
[torvalds@linux-foundation.org: use maybe_mkwrite]
Cc: stable@vger.kernel.org
Signed-off-by: Mel Gorman <mgorman@suse.de>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull vfs fixes from Al Viro:
"Assorted fixes + unifying __d_move() and __d_materialise_dentry() +
minimal regression fix for d_path() of victims of overwriting rename()
ported on top of that"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
vfs: Don't exchange "short" filenames unconditionally.
fold swapping ->d_name.hash into switch_names()
fold unlocking the children into dentry_unlock_parents_for_move()
kill __d_materialise_dentry()
__d_materialise_dentry(): flip the order of arguments
__d_move(): fold manipulations with ->d_child/->d_subdirs
don't open-code d_rehash() in d_materialise_unique()
pull rehashing and unlocking the target dentry into __d_materialise_dentry()
ufs: deal with nfsd/iget races
fuse: honour max_read and max_write in direct_io mode
shmem: fix nlink for rename overwrite directory
Pull cgroup fixes from Tejun Heo:
"This is quite late but these need to be backported anyway.
This is the fix for a long-standing cpuset bug which existed from
2009. cpuset makes use of PF_SPREAD_{PAGE|SLAB} flags to modify the
task's memory allocation behavior according to the settings of the
cpuset it belongs to; unfortunately, when those flags have to be
changed, cpuset did so directly even whlie the target task is running,
which is obviously racy as task->flags may be modified by the task
itself at any time. This obscure bug manifested as corrupt
PF_USED_MATH flag leading to a weird crash.
The bug is fixed by moving the flag to task->atomic_flags. The first
two are prepatory ones to help defining atomic_flags accessors and the
third one is the actual fix"
* 'for-3.17-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cpuset: PF_SPREAD_PAGE and PF_SPREAD_SLAB should be atomic flags
sched: add macros to define bitops for task atomic flags
sched: fix confusing PFA_NO_NEW_PRIVS constant
The third argument of fuse_get_user_pages() "nbytesp" refers to the number of
bytes a caller asked to pack into fuse request. This value may be lesser
than capacity of fuse request or iov_iter. So fuse_get_user_pages() must
ensure that *nbytesp won't grow.
Now, when helper iov_iter_get_pages() performs all hard work of extracting
pages from iov_iter, it can be done by passing properly calculated
"maxsize" to the helper.
The other caller of iov_iter_get_pages() (dio_refill_pages()) doesn't need
this capability, so pass LONG_MAX as the maxsize argument here.
Fixes: c9c37e2e63 ("fuse: switch to iov_iter_get_pages()")
Reported-by: Werner Baumann <werner.baumann@onlinehome.de>
Tested-by: Maxim Patlasov <mpatlasov@parallels.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
If overwriting an empty directory with rename, then need to drop the extra
nlink.
Test prog:
#include <stdio.h>
#include <fcntl.h>
#include <err.h>
#include <sys/stat.h>
int main(void)
{
const char *test_dir1 = "test-dir1";
const char *test_dir2 = "test-dir2";
int res;
int fd;
struct stat statbuf;
res = mkdir(test_dir1, 0777);
if (res == -1)
err(1, "mkdir(\"%s\")", test_dir1);
res = mkdir(test_dir2, 0777);
if (res == -1)
err(1, "mkdir(\"%s\")", test_dir2);
fd = open(test_dir2, O_RDONLY);
if (fd == -1)
err(1, "open(\"%s\")", test_dir2);
res = rename(test_dir1, test_dir2);
if (res == -1)
err(1, "rename(\"%s\", \"%s\")", test_dir1, test_dir2);
res = fstat(fd, &statbuf);
if (res == -1)
err(1, "fstat(%i)", fd);
if (statbuf.st_nlink != 0) {
fprintf(stderr, "nlink is %lu, should be 0\n", statbuf.st_nlink);
return 1;
}
return 0;
}
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This fixes the same bug as b43790eedd ("mm: softdirty: don't forget to
save file map softdiry bit on unmap") and 9aed8614af ("mm/memory.c:
don't forget to set softdirty on file mapped fault") where the return
value of pte_*mksoft_dirty was being ignored.
To be sure that no other pte/pmd "mk" function return values were being
ignored, I annotated the functions in arch/x86/include/asm/pgtable.h
with __must_check and rebuilt.
The userspace effect of this bug is that the softdirty mark might be
lost if a file mapped pte get zapped.
Signed-off-by: Peter Feiner <pfeiner@google.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Jamie Liu <jamieliu@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: <stable@vger.kernel.org> [3.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In commit c1221321b7
sched: Allow wait_on_bit_action() functions to support a timeout
I suggested that a "wait_on_bit_timeout()" interface would not meet my
need. This isn't true - I was just over-engineering.
Including a 'private' field in wait_bit_key instead of a focused
"timeout" field was just premature generalization. If some other
use is ever found, it can be generalized or added later.
So this patch renames "private" to "timeout" with a meaning "stop
waiting when "jiffies" reaches or passes "timeout",
and adds two of the many possible wait..bit..timeout() interfaces:
wait_on_page_bit_killable_timeout(), which is the one I want to use,
and out_of_line_wait_on_bit_timeout() which is a reasonably general
example. Others can be added as needed.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: NeilBrown <neilb@suse.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
When we change cpuset.memory_spread_{page,slab}, cpuset will flip
PF_SPREAD_{PAGE,SLAB} bit of tsk->flags for each task in that cpuset.
This should be done using atomic bitops, but currently we don't,
which is broken.
Tetsuo reported a hard-to-reproduce kernel crash on RHEL6, which happened
when one thread tried to clear PF_USED_MATH while at the same time another
thread tried to flip PF_SPREAD_PAGE/PF_SPREAD_SLAB. They both operate on
the same task.
Here's the full report:
https://lkml.org/lkml/2014/9/19/230
To fix this, we make PF_SPREAD_PAGE and PF_SPREAD_SLAB atomic flags.
v4:
- updated mm/slab.c. (Fengguang Wu)
- updated Documentation.
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Miao Xie <miaox@cn.fujitsu.com>
Cc: Kees Cook <keescook@chromium.org>
Fixes: 950592f7b9 ("cpusets: update tasks' page/slab spread flags in time")
Cc: <stable@vger.kernel.org> # 2.6.31+
Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
This is to receive 0a30288da1 ("blk-mq, percpu_ref: implement a
kludge for SCSI blk-mq stall during probe") which implements
__percpu_ref_kill_expedited() to work around SCSI blk-mq stall. The
commit reverted and patches to implement proper fix will be added.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Kent Overstreet <kmo@daterainc.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Christoph Hellwig <hch@lst.de>
1. We were calling clear_flush_young_notify in unmap_one, but we are
within an mmu notifier invalidate range scope. The spte exists no more
(due to range_start) and the accessed bit info has already been
propagated (due to kvm_pfn_set_accessed). Simply call
clear_flush_young.
2. We clear_flush_young on a primary MMU PMD, but this may be mapped
as a collection of PTEs by the secondary MMU (e.g. during log-dirty).
This required expanding the interface of the clear_flush_young mmu
notifier, so a lot of code has been trivially touched.
3. In the absence of shadow_accessed_mask (e.g. EPT A bit), we emulate
the access bit by blowing the spte. This requires proper synchronizing
with MMU notifier consumers, like every other removal of spte's does.
Signed-off-by: Andres Lagar-Cavilla <andreslc@google.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
When KVM handles a tdp fault it uses FOLL_NOWAIT. If the guest memory
has been swapped out or is behind a filemap, this will trigger async
readahead and return immediately. The rationale is that KVM will kick
back the guest with an "async page fault" and allow for some other
guest process to take over.
If async PFs are enabled the fault is retried asap from an async
workqueue. If not, it's retried immediately in the same code path. In
either case the retry will not relinquish the mmap semaphore and will
block on the IO. This is a bad thing, as other mmap semaphore users
now stall as a function of swap or filemap latency.
This patch ensures both the regular and async PF path re-enter the
fault allowing for the mmap semaphore to be relinquished in the case
of IO wait.
Reviewed-by: Radim Krčmář <rkrcmar@redhat.com>
Signed-off-by: Andres Lagar-Cavilla <andreslc@google.com>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Pull KVM fixes from Paolo Bonzini:
"Two very simple bugfixes, affecting all supported architectures"
[ Two? There's three commits in here. Oh well, I guess Paolo didn't
count the preparatory symbol export ]
* tag 'for-linus' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
KVM: correct null pid check in kvm_vcpu_yield_to()
KVM: check for !is_zero_pfn() in kvm_is_mmio_pfn()
mm: export symbol dependencies of is_zero_pfn()
This reverts commit 3189eddbca ("percpu: free percpu allocation info for
uniprocessor system").
The commit causes a hang with a crisv32 image. This may be an architecture
problem, but at least for now the revert is necessary to be able to boot a
crisv32 image.
Cc: Tejun Heo <tj@kernel.org>
Cc: Honggang Li <enjoymindful@gmail.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Tejun Heo <tj@kernel.org>
Fixes: 3189eddbca ("percpu: free percpu allocation info for uniprocessor system")
Cc: stable@vger.kernel.org # Please don't apply 3189eddbca
After we implemented default unified hierarchy, cgrp->kn can never
be NULL.
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
dma_pool_create() needs to unlock the mutex in error case. The bug was
introduced in the 3.16 by commit cc6b664aa2 ("mm/dmapool.c: remove
redundant NULL check for dev in dma_pool_create()")/
Signed-off-by: Krzysztof Hałasa <khc@piap.pl>
Cc: stable@vger.kernel.org # v3.16
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The setup_node_data() function allocates a pg_data_t object,
inserts it into the node_data[] array and initializes the
following fields: node_id, node_start_pfn and
node_spanned_pages.
However, a few function calls later during the kernel boot,
free_area_init_node() re-initializes those fields, possibly with
setup_node_data() is not used.
This causes a small glitch when running Linux as a hyperv numa
guest:
SRAT: PXM 0 -> APIC 0x00 -> Node 0
SRAT: PXM 0 -> APIC 0x01 -> Node 0
SRAT: PXM 1 -> APIC 0x02 -> Node 1
SRAT: PXM 1 -> APIC 0x03 -> Node 1
SRAT: Node 0 PXM 0 [mem 0x00000000-0x7fffffff]
SRAT: Node 1 PXM 1 [mem 0x80200000-0xf7ffffff]
SRAT: Node 1 PXM 1 [mem 0x100000000-0x1081fffff]
NUMA: Node 1 [mem 0x80200000-0xf7ffffff] + [mem 0x100000000-0x1081fffff] -> [mem 0x80200000-0x1081fffff]
Initmem setup node 0 [mem 0x00000000-0x7fffffff]
NODE_DATA [mem 0x7ffdc000-0x7ffeffff]
Initmem setup node 1 [mem 0x80800000-0x1081fffff]
NODE_DATA [mem 0x1081ea000-0x1081fdfff]
crashkernel: memory value expected
[ffffea0000000000-ffffea0001ffffff] PMD -> [ffff88007de00000-ffff88007fdfffff] on node 0
[ffffea0002000000-ffffea00043fffff] PMD -> [ffff880105600000-ffff8801077fffff] on node 1
Zone ranges:
DMA [mem 0x00001000-0x00ffffff]
DMA32 [mem 0x01000000-0xffffffff]
Normal [mem 0x100000000-0x1081fffff]
Movable zone start for each node
Early memory node ranges
node 0: [mem 0x00001000-0x0009efff]
node 0: [mem 0x00100000-0x7ffeffff]
node 1: [mem 0x80200000-0xf7ffffff]
node 1: [mem 0x100000000-0x1081fffff]
On node 0 totalpages: 524174
DMA zone: 64 pages used for memmap
DMA zone: 21 pages reserved
DMA zone: 3998 pages, LIFO batch:0
DMA32 zone: 8128 pages used for memmap
DMA32 zone: 520176 pages, LIFO batch:31
On node 1 totalpages: 524288
DMA32 zone: 7672 pages used for memmap
DMA32 zone: 491008 pages, LIFO batch:31
Normal zone: 520 pages used for memmap
Normal zone: 33280 pages, LIFO batch:7
In this dmesg, the SRAT table reports that the memory range for
node 1 starts at 0x80200000. However, the line starting with
"Initmem" reports that node 1 memory range starts at 0x80800000.
The "Initmem" line is reported by setup_node_data() and is
wrong, because the kernel ends up using the range as reported in
the SRAT table.
This commit drops all that dead code from setup_node_data(),
renames it to alloc_node_data() and adds a printk() to
free_area_init_node() so that we report a node's memory range
accurately.
Here's the same dmesg section with this patch applied:
SRAT: PXM 0 -> APIC 0x00 -> Node 0
SRAT: PXM 0 -> APIC 0x01 -> Node 0
SRAT: PXM 1 -> APIC 0x02 -> Node 1
SRAT: PXM 1 -> APIC 0x03 -> Node 1
SRAT: Node 0 PXM 0 [mem 0x00000000-0x7fffffff]
SRAT: Node 1 PXM 1 [mem 0x80200000-0xf7ffffff]
SRAT: Node 1 PXM 1 [mem 0x100000000-0x1081fffff]
NUMA: Node 1 [mem 0x80200000-0xf7ffffff] + [mem 0x100000000-0x1081fffff] -> [mem 0x80200000-0x1081fffff]
NODE_DATA(0) allocated [mem 0x7ffdc000-0x7ffeffff]
NODE_DATA(1) allocated [mem 0x1081ea000-0x1081fdfff]
crashkernel: memory value expected
[ffffea0000000000-ffffea0001ffffff] PMD -> [ffff88007de00000-ffff88007fdfffff] on node 0
[ffffea0002000000-ffffea00043fffff] PMD -> [ffff880105600000-ffff8801077fffff] on node 1
Zone ranges:
DMA [mem 0x00001000-0x00ffffff]
DMA32 [mem 0x01000000-0xffffffff]
Normal [mem 0x100000000-0x1081fffff]
Movable zone start for each node
Early memory node ranges
node 0: [mem 0x00001000-0x0009efff]
node 0: [mem 0x00100000-0x7ffeffff]
node 1: [mem 0x80200000-0xf7ffffff]
node 1: [mem 0x100000000-0x1081fffff]
Initmem setup node 0 [mem 0x00001000-0x7ffeffff]
On node 0 totalpages: 524174
DMA zone: 64 pages used for memmap
DMA zone: 21 pages reserved
DMA zone: 3998 pages, LIFO batch:0
DMA32 zone: 8128 pages used for memmap
DMA32 zone: 520176 pages, LIFO batch:31
Initmem setup node 1 [mem 0x80200000-0x1081fffff]
On node 1 totalpages: 524288
DMA32 zone: 7672 pages used for memmap
DMA32 zone: 491008 pages, LIFO batch:31
Normal zone: 520 pages used for memmap
Normal zone: 33280 pages, LIFO batch:7
This commit was tested on a two node bare-metal NUMA machine and
Linux as a numa guest on hyperv and qemu/kvm.
PS: The wrong memory range reported by setup_node_data() seems to be
harmless in the current kernel because it's just not used. However,
that bad range is used in kernel 2.6.32 to initialize the old boot
memory allocator, which causes a crash during boot.
Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
In order to make the static inline function is_zero_pfn() callable by
modules, export its symbol dependencies 'zero_pfn' and (for s390 and
mips) 'zero_page_mask'.
We need this for KVM, as CONFIG_KVM is a tristate for all supported
architectures except ARM and arm64, and testing a pfn whether it refers
to the zero page is required to correctly distinguish the zero page
from other special RAM ranges that may also have the PG_reserved bit
set, but need to be treated as MMIO memory.
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
A bit of churn on the for-linus side that would be nice to have
in the core bits for 3.18, so pull it in to catch us up and make
forward progress easier.
Signed-off-by: Jens Axboe <axboe@fb.com>
Conflicts:
block/scsi_ioctl.c
Make sure we actually see the output of validate_mm() and browse_rb()
before triggering a BUG(). pr_info isn't shown by default so the reason
for the BUG() isn't obvious.
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Let memblock skip the hotpluggable memory regions in __next_mem_range(),
it is used to to prevent memblock from allocating hotpluggable memory
for the kernel at early time. The code is the same as __next_mem_range_rev().
Clear hotpluggable flag before releasing free pages to the buddy
allocator. If we don't clear hotpluggable flag in
free_low_memory_core_early(), the memory which marked hotpluggable flag
will not free to buddy allocator. Because __next_mem_range() will skip
them.
free_low_memory_core_early
for_each_free_mem_range
for_each_mem_range
__next_mem_range
[akpm@linux-foundation.org: fix warning]
Signed-off-by: Xishi Qiu <qiuxishi@huawei.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch fix spelling typo found in DocBook/kernel-api.xml.
It is because the file is generated from the source comments,
I have to fix the comments in source codes.
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
While updating locking, b38d08f318 ("percpu: restructure locking")
broke pcpu_create_chunk() creation path in pcpu_alloc(). It returns
without releasing pcpu_alloc_mutex. Fix it.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Julia Lawall <julia.lawall@lip6.fr>
A block_device may be attached to different gendisks and thus
different bdis over time. bdev_inode_switch_bdi() is used to switch
the associated bdi. The function assumes that the inode could be
dirty and transfers it between bdis if so. This is a bit nasty in
that it reaches into bdi internals.
This patch reimplements the function so that it writes out the inode
if dirty. This is a lot simpler and can be implemented without
exposing bdi internals.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Jens Axboe <axboe@fb.com>
bdi_destroy() has code to transfer the remaining dirty inodes to the
default_backing_dev_info; however, given the shutdown sequence, it
isn't clear how such condition would happen. Also, it isn't a full
solution as the transferred inodes stlil point to the bdi which is
being destroyed. Operations on those inodes can end up accessing
already released fields such as the percpu stat fields.
Digging through the history, it seems that the code was added as a
quick workaround for a bug report without fully root-causing the
issue. We probably want to remove the code in time but for now let's
add a comment noting that it is a quick workaround.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
Canceling of bdi->wb.dwork is currently a bit mushy.
bdi_wb_shutdown() performs cancel_delayed_work_sync() at the end after
shutting down and flushing the delayed_work and bdi_destroy() tries
yet again after bdi_unregister().
bdi->wb.dwork is queued only after checking BDI_registered while
holding bdi->wb_lock and bdi_wb_shutdown() clears the flag while
holding the same lock and then flushes the delayed_work. There's no
way the delayed_work can be queued again after that.
Replace the two unnecessary cancel_delayed_work_sync() invocations
with WARNs on pending. This simplifies and clarifies the code a bit
and will help future changes in further isolating bdi_writeback
handling.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
The only places where NULL test on bdi->dev is used are
bdi_[un]register(). The functions can't be called in parallel anyway
and there's no point in protecting bdi->dev clearing with a lock.
Remove bdi->wb_lock grabbing around bdi->dev clearing and move it
after device_unregister() call so that bdi->dev doesn't have to be
cached in a local variable.
This patch shouldn't introduce any behavior difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
Pull percpu fixes from Tejun Heo:
"One patch to fix a failure path in the alloc path. The bug is
dangerous but probably not too likely to actually trigger in the wild
given that there hasn't been any report yet.
The other two are low impact fixes"
* 'for-3.17-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu:
percpu: free percpu allocation info for uniprocessor system
percpu: perform tlb flush after pcpu_map_pages() failure
percpu: fix pcpu_alloc_pages() failure path
Percpu allocator now supports allocation mask. Add @gfp to
[flex_]proportions init functions so that !GFP_KERNEL allocation masks
can be used with them too.
This patch doesn't make any functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Percpu allocator now supports allocation mask. Add @gfp to
percpu_counter_init() so that !GFP_KERNEL allocation masks can be used
with percpu_counters too.
We could have left percpu_counter_init() alone and added
percpu_counter_init_gfp(); however, the number of users isn't that
high and introducing _gfp variants to all percpu data structures would
be quite ugly, so let's just do the conversion. This is the one with
the most users. Other percpu data structures are a lot easier to
convert.
This patch doesn't make any functional difference.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jan Kara <jack@suse.cz>
Acked-by: "David S. Miller" <davem@davemloft.net>
Cc: x86@kernel.org
Cc: Jens Axboe <axboe@kernel.dk>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Morton <akpm@linux-foundation.org>
RCU-tasks requires the occasional voluntary context switch
from CPU-bound in-kernel tasks. In some cases, this requires
instrumenting cond_resched(). However, there is some reluctance
to countenance unconditionally instrumenting cond_resched() (see
http://lwn.net/Articles/603252/), so this commit creates a separate
cond_resched_rcu_qs() that may be used in place of cond_resched() in
locations prone to long-duration in-kernel looping.
This commit currently instruments only RCU-tasks. Future possibilities
include also instrumenting RCU, RCU-bh, and RCU-sched in order to reduce
IPI usage.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Dave Hansen reports a massive scalability regression in an uncontained
page fault benchmark with more than 30 concurrent threads, which he
bisected down to 05b8430123 ("mm: memcontrol: use root_mem_cgroup
res_counter") and pin-pointed on res_counter spinlock contention.
That change relied on the per-cpu charge caches to mostly swallow the
res_counter costs, but it's apparent that the caches don't scale yet.
Revert memcg back to bypassing res_counters on the root level in order
to restore performance for uncontained workloads.
Reported-by: Dave Hansen <dave@sr71.net>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Dave Hansen <dave.hansen@intel.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The percpu allocator now supports atomic allocations by only
allocating from already populated areas but the mechanism to ensure
that there's adequate amount of populated areas was missing.
This patch expands pcpu_balance_work so that in addition to freeing
excess free chunks it also populates chunks to maintain an adequate
level of populated areas. pcpu_alloc() schedules pcpu_balance_work if
the amount of free populated areas is too low or after an atomic
allocation failure.
* PERPCU_DYNAMIC_RESERVE is increased by two pages to account for
PCPU_EMPTY_POP_PAGES_LOW.
* pcpu_async_enabled is added to gate both async jobs -
chunk->map_extend_work and pcpu_balance_work - so that we don't end
up scheduling them while the needed subsystems aren't up yet.
Signed-off-by: Tejun Heo <tj@kernel.org>
pcpu_reclaim_work will also be used to populate chunks asynchronously.
Rename it to pcpu_balance_work in preparation. pcpu_reclaim() is
renamed to pcpu_balance_workfn() and some of its local variables are
renamed too.
This is pure rename.
Signed-off-by: Tejun Heo <tj@kernel.org>
pcpu_nr_empty_pop_pages counts the number of empty populated pages
across all chunks and chunk->nr_populated counts the number of
populated pages in a chunk. Both will be used to implement pre/async
population for atomic allocations.
pcpu_chunk_[de]populated() are added to update chunk->populated,
chunk->nr_populated and pcpu_nr_empty_pop_pages together. All
successful chunk [de]populations should be followed by the
corresponding pcpu_chunk_[de]populated() calls.
Signed-off-by: Tejun Heo <tj@kernel.org>
An allocation attempt may require extending chunk->map array which
requires GFP_KERNEL context which isn't available for atomic
allocations. This patch ensures that chunk->map array usually keeps
some amount of available space by directly allocating buffer space
during GFP_KERNEL allocations and scheduling async extension during
atomic ones. This should make atomic allocation failures from map
space exhaustion rare.
Signed-off-by: Tejun Heo <tj@kernel.org>
Now that pcpu_alloc_area() can allocate only from populated areas,
it's easy to add atomic allocation support to [__]alloc_percpu().
Update pcpu_alloc() so that it accepts @gfp and skips all the blocking
operations and allocates only from the populated areas if @gfp doesn't
contain GFP_KERNEL. New interface functions [__]alloc_percpu_gfp()
are added.
While this means that atomic allocations are possible, this isn't
complete yet as there's no mechanism to ensure that certain amount of
populated areas is kept available and atomic allocations may keep
failing under certain conditions.
Signed-off-by: Tejun Heo <tj@kernel.org>
The next patch will conditionalize the population block in
pcpu_alloc() which will end up making a rather large indentation
change obfuscating the actual logic change. This patch puts the block
under "if (true)" so that the next patch can avoid indentation
changes. The defintions of the local variables which are used only in
the block are moved into the block.
This patch is purely cosmetic.
Signed-off-by: Tejun Heo <tj@kernel.org>
Update pcpu_alloc_area() so that it can skip unpopulated areas if the
new parameter @pop_only is true. This is implemented by a new
function, pcpu_fit_in_area(), which determines the amount of head
padding considering the alignment and populated state.
@pop_only is currently always false but this will be used to implement
atomic allocation.
Signed-off-by: Tejun Heo <tj@kernel.org>
At first, the percpu allocator required a sleepable context for both
alloc and free paths and used pcpu_alloc_mutex to protect everything.
Later, pcpu_lock was introduced to protect the index data structure so
that the free path can be invoked from atomic contexts. The
conversion only updated what's necessary and left most of the
allocation path under pcpu_alloc_mutex.
The percpu allocator is planned to add support for atomic allocation
and this patch restructures locking so that the coverage of
pcpu_alloc_mutex is further reduced.
* pcpu_alloc() now grab pcpu_alloc_mutex only while creating a new
chunk and populating the allocated area. Everything else is now
protected soley by pcpu_lock.
After this change, multiple instances of pcpu_extend_area_map() may
race but the function already implements sufficient synchronization
using pcpu_lock.
This also allows multiple allocators to arrive at new chunk
creation. To avoid creating multiple empty chunks back-to-back, a
new chunk is created iff there is no other empty chunk after
grabbing pcpu_alloc_mutex.
* pcpu_lock is now held while modifying chunk->populated bitmap.
After this, all data structures are protected by pcpu_lock.
Signed-off-by: Tejun Heo <tj@kernel.org>
percpu-km instantiates the whole chunk on creation and doesn't make
use of chunk->populated bitmap and leaves it as zero. While this
currently doesn't cause any problem, the inconsistency makes it
difficult to build further logic on top of chunk->populated. This
patch makes percpu-km fill chunk->populated on creation so that the
bitmap is always consistent.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Christoph Lameter <cl@linux.com>
Previously, pcpu_[de]populate_chunk() were called with the range which
may contain multiple target regions in it and
pcpu_[de]populate_chunk() iterated over the regions. This has the
benefit of batching up cache flushes for all the regions; however,
we're planning to add more bookkeeping logic around [de]population to
support atomic allocations and this delegation of iterations gets in
the way.
This patch moves the region iterations out of
pcpu_[de]populate_chunk() into its callers - pcpu_alloc() and
pcpu_reclaim() - so that we can later add logic to track more states
around them. This change may make cache and tlb flushes more frequent
but multi-region [de]populations are rare anyway and if this actually
becomes a problem, it's not difficult to factor out cache flushes as
separate callbacks which are directly invoked from percpu.c.
Signed-off-by: Tejun Heo <tj@kernel.org>
percpu-vm and percpu-km implement separate versions of
pcpu_[de]populate_chunk() and some part which is or should be common
are currently in the specific implementations. Make the following
changes.
* Allocate area clearing is moved from the pcpu_populate_chunk()
implementations to pcpu_alloc(). This makes percpu-km's version
noop.
* Quick exit tests in pcpu_[de]populate_chunk() of percpu-vm are moved
to their respective callers so that they are applied to percpu-km
too. This doesn't make any meaningful difference as both functions
are noop for percpu-km; however, this is more consistent and will
help implementing atomic allocation support.
Signed-off-by: Tejun Heo <tj@kernel.org>
pcpu_get_pages() creates the temp pages array if not already allocated
and returns the pointer to it. As the function is called from both
[de]population paths and depopulation can only happen after at least
one successful population, the param doesn't make any difference - the
allocation will always happen on the population path anyway.
Remove @may_alloc from pcpu_get_pages(). Also, add an lockdep
assertion pcpu_alloc_mutex instead of vaguely stating that the
exclusion is the caller's responsibility.
Signed-off-by: Tejun Heo <tj@kernel.org>
