Pull tracing fixes from Steven Rostedt:
"There was some breakage with the changes for jump labels in the 4.11
merge window:
- powerpc broke as jump labels uses the two LSB bits as flags in
initialization.
A check was added to make sure that all jump label entries were 4
bytes aligned, but powerpc didn't work that way for modules. Adding
an alignment in the module linker script appeared to be the best
solution.
- Jump labels also added an anonymous union to access those LSB bits
as a normal long. But because this structure had static
initialization, it broke older compilers that could not statically
initialize anonymous unions without brackets.
- The command line parameter for setting function graph filter broke
the "EMPTY_HASH" descriptor by modifying it instead of creating a
new hash to hold the entries.
- The command line parameter ftrace_graph_max_depth was added to
allow its setting at boot time. It uses existing code and only the
command line hook was added.
This is not really a fix, but as it uses existing code without
affecting anything else, I added it to this release. It was ready
before the merge window closed, but I wanted to let it sit in
linux-next for a couple of days first"
* tag 'trace-v4.11-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
ftrace/graph: Add ftrace_graph_max_depth kernel parameter
tracing: Add #undef to fix compile error
jump_label: Add comment about initialization order for anonymous unions
jump_label: Fix anonymous union initialization
module: set __jump_table alignment to 8
ftrace/graph: Do not modify the EMPTY_HASH for the function_graph filter
tracing: Fix code comment for ftrace_ops_get_func()
Pull networking fixes from David Miller:
1) Fix double-free in batman-adv, from Sven Eckelmann.
2) Fix packet stats for fast-RX path, from Joannes Berg.
3) Netfilter's ip_route_me_harder() doesn't handle request sockets
properly, fix from Florian Westphal.
4) Fix sendmsg deadlock in rxrpc, from David Howells.
5) Add missing RCU locking to transport hashtable scan, from Xin Long.
6) Fix potential packet loss in mlxsw driver, from Ido Schimmel.
7) Fix race in NAPI handling between poll handlers and busy polling,
from Eric Dumazet.
8) TX path in vxlan and geneve need proper RCU locking, from Jakub
Kicinski.
9) SYN processing in DCCP and TCP need to disable BH, from Eric
Dumazet.
10) Properly handle net_enable_timestamp() being invoked from IRQ
context, also from Eric Dumazet.
11) Fix crash on device-tree systems in xgene driver, from Alban Bedel.
12) Do not call sk_free() on a locked socket, from Arnaldo Carvalho de
Melo.
13) Fix use-after-free in netvsc driver, from Dexuan Cui.
14) Fix max MTU setting in bonding driver, from WANG Cong.
15) xen-netback hash table can be allocated from softirq context, so use
GFP_ATOMIC. From Anoob Soman.
16) Fix MAC address change bug in bgmac driver, from Hari Vyas.
17) strparser needs to destroy strp_wq on module exit, from WANG Cong.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (69 commits)
strparser: destroy workqueue on module exit
sfc: fix IPID endianness in TSOv2
sfc: avoid max() in array size
rds: remove unnecessary returned value check
rxrpc: Fix potential NULL-pointer exception
nfp: correct DMA direction in XDP DMA sync
nfp: don't tell FW about the reserved buffer space
net: ethernet: bgmac: mac address change bug
net: ethernet: bgmac: init sequence bug
xen-netback: don't vfree() queues under spinlock
xen-netback: keep a local pointer for vif in backend_disconnect()
netfilter: nf_tables: don't call nfnetlink_set_err() if nfnetlink_send() fails
netfilter: nft_set_rbtree: incorrect assumption on lower interval lookups
netfilter: nf_conntrack_sip: fix wrong memory initialisation
can: flexcan: fix typo in comment
can: usb_8dev: Fix memory leak of priv->cmd_msg_buffer
can: gs_usb: fix coding style
can: gs_usb: Don't use stack memory for USB transfers
ixgbe: Limit use of 2K buffers on architectures with 256B or larger cache lines
ixgbe: update the rss key on h/w, when ethtool ask for it
...
There are several trace include files that define TRACE_INCLUDE_FILE.
Include several of them in the same .c file (as I currently have in
some code I am working on), and the compile will blow up with a
"warning: "TRACE_INCLUDE_FILE" redefined #define TRACE_INCLUDE_FILE syscalls"
Every other include file in include/trace/events/ avoids that issue
by having a #undef TRACE_INCLUDE_FILE before the #define; syscalls.h
should have one, too.
Link: http://lkml.kernel.org/r/20160928225554.13bd7ac6@annuminas.surriel.com
Cc: stable@vger.kernel.org
Fixes: b8007ef742 ("tracing: Separate raw syscall from syscall tracer")
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
We are going to split <linux/sched/numa_balancing.h> out of <linux/sched.h>, which
will have to be picked up from other headers and a couple of .c files.
Create a trivial placeholder <linux/sched/numa_balancing.h> file that just
maps to <linux/sched.h> to make this patch obviously correct and
bisectable.
Include the new header in the files that are going to need it.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull f2fs updates from Jaegeuk Kim:
"This round introduces several interesting features such as on-disk NAT
bitmaps, IO alignment, and a discard thread. And it includes a couple
of major bug fixes as below.
Enhancements:
- introduce on-disk bitmaps to avoid scanning NAT blocks when getting
free nids
- support IO alignment to prepare open-channel SSD integration in
future
- introduce a discard thread to avoid long latency during checkpoint
and fstrim
- use SSR for warm node and enable inline_xattr by default
- introduce in-memory bitmaps to check FS consistency for debugging
- improve write_begin by avoiding needless read IO
Bug fixes:
- fix broken zone_reset behavior for SMR drive
- fix wrong victim selection policy during GC
- fix missing behavior when preparing discard commands
- fix bugs in atomic write support and fiemap
- workaround to handle multiple f2fs_add_link calls having same name
... and it includes a bunch of clean-up patches as well"
* tag 'for-f2fs-4.11' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (97 commits)
f2fs: avoid to flush nat journal entries
f2fs: avoid to issue redundant discard commands
f2fs: fix a plint compile warning
f2fs: add f2fs_drop_inode tracepoint
f2fs: Fix zoned block device support
f2fs: remove redundant set_page_dirty()
f2fs: fix to enlarge size of write_io_dummy mempool
f2fs: fix memory leak of write_io_dummy mempool during umount
f2fs: fix to update F2FS_{CP_}WB_DATA count correctly
f2fs: use MAX_FREE_NIDS for the free nids target
f2fs: introduce free nid bitmap
f2fs: new helper cur_cp_crc() getting crc in f2fs_checkpoint
f2fs: update the comment of default nr_pages to skipping
f2fs: drop the duplicate pval in f2fs_getxattr
f2fs: Don't update the xattr data that same as the exist
f2fs: kill __is_extent_same
f2fs: avoid bggc->fggc when enough free segments are avaliable after cp
f2fs: select target segment with closer temperature in SSR mode
f2fs: show simple call stack in fault injection message
f2fs: no need lock_op in f2fs_write_inline_data
...
All the routines by which rxrpc is accessed from the outside are serialised
by means of the socket lock (sendmsg, recvmsg, bind,
rxrpc_kernel_begin_call(), ...) and this presents a problem:
(1) If a number of calls on the same socket are in the process of
connection to the same peer, a maximum of four concurrent live calls
are permitted before further calls need to wait for a slot.
(2) If a call is waiting for a slot, it is deep inside sendmsg() or
rxrpc_kernel_begin_call() and the entry function is holding the socket
lock.
(3) sendmsg() and recvmsg() or the in-kernel equivalents are prevented
from servicing the other calls as they need to take the socket lock to
do so.
(4) The socket is stuck until a call is aborted and makes its slot
available to the waiter.
Fix this by:
(1) Provide each call with a mutex ('user_mutex') that arbitrates access
by the users of rxrpc separately for each specific call.
(2) Make rxrpc_sendmsg() and rxrpc_recvmsg() unlock the socket as soon as
they've got a call and taken its mutex.
Note that I'm returning EWOULDBLOCK from recvmsg() if MSG_DONTWAIT is
set but someone else has the lock. Should I instead only return
EWOULDBLOCK if there's nothing currently to be done on a socket, and
sleep in this particular instance because there is something to be
done, but we appear to be blocked by the interrupt handler doing its
ping?
(3) Make rxrpc_new_client_call() unlock the socket after allocating a new
call, locking its user mutex and adding it to the socket's call tree.
The call is returned locked so that sendmsg() can add data to it
immediately.
From the moment the call is in the socket tree, it is subject to
access by sendmsg() and recvmsg() - even if it isn't connected yet.
(4) Lock new service calls in the UDP data_ready handler (in
rxrpc_new_incoming_call()) because they may already be in the socket's
tree and the data_ready handler makes them live immediately if a user
ID has already been preassigned.
Note that the new call is locked before any notifications are sent
that it is live, so doing mutex_trylock() *ought* to always succeed.
Userspace is prevented from doing sendmsg() on calls that are in a
too-early state in rxrpc_do_sendmsg().
(5) Make rxrpc_new_incoming_call() return the call with the user mutex
held so that a ping can be scheduled immediately under it.
Note that it might be worth moving the ping call into
rxrpc_new_incoming_call() and then we can drop the mutex there.
(6) Make rxrpc_accept_call() take the lock on the call it is accepting and
release the socket after adding the call to the socket's tree. This
is slightly tricky as we've dequeued the call by that point and have
to requeue it.
Note that requeuing emits a trace event.
(7) Make rxrpc_kernel_send_data() and rxrpc_kernel_recv_data() take the
new mutex immediately and don't bother with the socket mutex at all.
This patch has the nice bonus that calls on the same socket are now to some
extent parallelisable.
Note that we might want to move rxrpc_service_prealloc() calls out from the
socket lock and give it its own lock, so that we don't hang progress in
other calls because we're waiting for the allocator.
We probably also want to avoid calling rxrpc_notify_socket() from within
the socket lock (rxrpc_accept_call()).
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Marc Dionne <marc.c.dionne@auristor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Pull tracing updates from Steven Rostedt:
"This release has no new tracing features, just clean ups, minor fixes
and small optimizations"
* tag 'trace-v4.11' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace: (25 commits)
tracing: Remove outdated ring buffer comment
tracing/probes: Fix a warning message to show correct maximum length
tracing: Fix return value check in trace_benchmark_reg()
tracing: Use modern function declaration
jump_label: Reduce the size of struct static_key
tracing/probe: Show subsystem name in messages
tracing/hwlat: Update old comment about migration
timers: Make flags output in the timer_start tracepoint useful
tracing: Have traceprobe_probes_write() not access userspace unnecessarily
tracing: Have COMM event filter key be treated as a string
ftrace: Have set_graph_function handle multiple functions in one write
ftrace: Do not hold references of ftrace_graph_{notrace_}hash out of graph_lock
tracing: Reset parser->buffer to allow multiple "puts"
ftrace: Have set_graph_functions handle write with RDWR
ftrace: Reset fgd->hash in ftrace_graph_write()
ftrace: Replace (void *)1 with a meaningful macro name FTRACE_GRAPH_EMPTY
ftrace: Create a slight optimization on searching the ftrace_hash
tracing: Add ftrace_hash_key() helper function
ftrace: Convert graph filter to use hash tables
ftrace: Expose ftrace_hash_empty and ftrace_lookup_ip
...
Pull btrfs updates from Chris Mason:
"This has a series of fixes and cleanups that Dave Sterba has been
collecting.
There is a pretty big variety here, cleaning up internal APIs and
fixing corner cases"
* 'for-linus-4.11' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs: (124 commits)
Btrfs: use the correct type when creating cow dio extent
Btrfs: fix deadlock between dedup on same file and starting writeback
btrfs: use btrfs_debug instead of pr_debug in transaction abort
btrfs: btrfs_truncate_free_space_cache always allocates path
btrfs: free-space-cache, clean up unnecessary root arguments
btrfs: convert btrfs_inc_block_group_ro to accept fs_info
btrfs: flush_space always takes fs_info->fs_root
btrfs: pass fs_info to (more) routines that are only called with extent_root
btrfs: qgroup: Move half of the qgroup accounting time out of commit trans
btrfs: remove unused parameter from adjust_slots_upwards
btrfs: remove unused parameters from __btrfs_write_out_cache
btrfs: remove unused parameter from cleanup_write_cache_enospc
btrfs: remove unused parameter from __add_inode_ref
btrfs: remove unused parameter from clone_copy_inline_extent
btrfs: remove unused parameters from btrfs_cmp_data
btrfs: remove unused parameter from __add_inline_refs
btrfs: remove unused parameters from scrub_setup_wr_ctx
btrfs: remove unused parameter from create_snapshot
btrfs: remove unused parameter from init_first_rw_device
btrfs: remove unused parameter from __btrfs_alloc_chunk
...
Memory pressure can put dirty pages at the end of the LRU without
anybody running into dirty limits. Don't start writing individual pages
from kswapd while the flushers might be asleep.
Unlike the old direct reclaim flusher wakeup (removed in the next patch)
that flushes the number of pages just scanned, this patch wakes the
flushers for all outstanding dirty pages. That seemed to perform better
in a synthetic test that pushes dirty pages to the end of the LRU and
into reclaim, because we know LRU aging outstrips writeback already, and
this way we give younger dirty pages a headstart rather than wait until
reclaim runs into them as well. It also means less plugging and risk of
exhausting the struct request pool from reclaim.
There is a concern that this will cause temporary files that used to get
dirtied and truncated before writeback to now get written to disk under
memory pressure. If this turns out to be a real problem, we'll have to
revisit this and tame the reclaim flusher wakeups.
[hannes@cmpxchg.org: mention dirty expiration as a condition]
Link: http://lkml.kernel.org/r/20170126174739.GA30636@cmpxchg.org
Link: http://lkml.kernel.org/r/20170123181641.23938-3-hannes@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We need to flush data writes before flushing last node block writes by using
FUA with PREFLUSH. We don't need to guarantee precedent node writes since if
those are not written, we can't reach to the last node block when scanning
node block chain during roll-forward recovery.
Afterwards f2fs_wait_on_page_writeback guarantees all the IO submission to
disk, which builds a valid node block chain.
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
mm_vmscan_lru_shrink_inactive will currently report the number of
scanned and reclaimed pages. This doesn't give us an idea how the
reclaim went except for the overall effectiveness though. Export and
show other counters which will tell us why we couldn't reclaim some
pages.
- nr_dirty, nr_writeback, nr_congested and nr_immediate tells
us how many pages are blocked due to IO
- nr_activate tells us how many pages were moved to the active
list
- nr_ref_keep reports how many pages are kept on the LRU due
to references (mostly for the file pages which are about to
go for another round through the inactive list)
- nr_unmap_fail - how many pages failed to unmap
All these are rather low level so they might change in future but the
tracepoint is already implementation specific so no tools should be
depending on its stability.
Link: http://lkml.kernel.org/r/20170104101942.4860-7-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm_vmscan_lru_isolate shows the number of requested, scanned and taken
pages. This is mostly OK but on 32b systems the number of scanned pages
is quite misleading because it includes both the scanned and skipped
pages. Moreover the skipped part is scaled based on the number of taken
pages. Let's report the exact numbers without any additional logic and
add the number of skipped pages.
This should make the reported data much more easier to interpret.
Link: http://lkml.kernel.org/r/20170104101942.4860-4-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Our reclaim process has several tracepoints to tell us more about how
things are progressing. We are, however, missing a tracepoint to track
active list aging. Introduce mm_vmscan_lru_shrink_active which reports
the number of
- nr_taken is number of isolated pages from the active list
- nr_referenced pages which tells us that we are hitting referenced
pages which are deactivated. If this is a large part of the
reported nr_deactivated pages then we might be hitting into
the active list too early because they might be still part of
the working set. This might help to debug performance issues.
- nr_active pages which tells us how many pages are kept on the
active list - mostly exec file backed pages. A high number can
indicate that we might be trashing on executables.
[mhocko@suse.com: update]
Link: http://lkml.kernel.org/r/20170104135244.GJ25453@dhcp22.suse.cz
Link: http://lkml.kernel.org/r/20170104101942.4860-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "vm, vmscan: enahance vmscan tracepoints", v2.
While debugging [2] I've realized that there is some room for
improvements in the tracepoints set we offer currently. I had hard
times to make any conclusion from the existing ones. The resulting
problem turned out to be active list aging [3] and we are missing at
least two tracepoints to debug such a problem.
Some existing tracepoints could export more information to see _why_ the
reclaim progress cannot be made not only _how much_ we could reclaim.
The later could be seen quite reasonably from the vmstat counters
already. It can be argued that we are showing too many implementation
details in those tracepoints but I consider them way too lowlevel
already to be usable by any kernel independent userspace. I would be
_really_ surprised if anything but debugging tools have used them.
Any feedback is highly appreciated.
[1] http://lkml.kernel.org/r/20161228153032.10821-1-mhocko@kernel.org
[2] http://lkml.kernel.org/r/20161215225702.GA27944@boerne.fritz.box
[3] http://lkml.kernel.org/r/20161223105157.GB23109@dhcp22.suse.cz
This patch (of 8):
The trace point is not used since 925b7673cc ("mm: make per-memcg LRU
lists exclusive") so it can be removed.
Link: http://lkml.kernel.org/r/20170104101942.4860-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Higher order requests oom debugging is currently quite hard. We do have
some compaction points which can tell us how the compaction is operating
but there is no trace point to tell us about compaction retry logic.
This patch adds a one which will have the following format
bash-3126 [001] .... 1498.220001: compact_retry: order=9 priority=COMPACT_PRIO_SYNC_LIGHT compaction_result=withdrawn retries=0 max_retries=16 should_retry=0
we can see that the order 9 request is not retried even though we are in
the highest compaction priority mode becase the last compaction attempt
was withdrawn. This means that compaction_zonelist_suitable must have
returned false and there is no suitable zone to compact for this request
and so no need to retry further.
another example would be
<...>-3137 [001] .... 81.501689: compact_retry: order=9 priority=COMPACT_PRIO_SYNC_LIGHT compaction_result=failed retries=0 max_retries=16 should_retry=0
in this case the order-9 compaction failed to find any suitable block.
We do not retry anymore because this is a costly request and those do
not go below COMPACT_PRIO_SYNC_LIGHT priority.
Link: http://lkml.kernel.org/r/20161220130135.15719-4-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
should_reclaim_retry is the central decision point for declaring the
OOM. It might be really useful to expose data used for this decision
making when debugging an unexpected oom situations.
Say we have an OOM report:
[ 52.264001] mem_eater invoked oom-killer: gfp_mask=0x24280ca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), nodemask=0, order=0, oom_score_adj=0
[ 52.267549] CPU: 3 PID: 3148 Comm: mem_eater Tainted: G W 4.8.0-oomtrace3-00006-gb21338b386d2 #1024
Now we can check the tracepoint data to see how we have ended up in this
situation:
mem_eater-3148 [003] .... 52.432801: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11134 min_wmark=11084 no_progress_loops=1 wmark_check=1
mem_eater-3148 [003] .... 52.433269: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11103 min_wmark=11084 no_progress_loops=1 wmark_check=1
mem_eater-3148 [003] .... 52.433712: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11100 min_wmark=11084 no_progress_loops=2 wmark_check=1
mem_eater-3148 [003] .... 52.434067: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11097 min_wmark=11084 no_progress_loops=3 wmark_check=1
mem_eater-3148 [003] .... 52.434414: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11094 min_wmark=11084 no_progress_loops=4 wmark_check=1
mem_eater-3148 [003] .... 52.434761: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11091 min_wmark=11084 no_progress_loops=5 wmark_check=1
mem_eater-3148 [003] .... 52.435108: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11087 min_wmark=11084 no_progress_loops=6 wmark_check=1
mem_eater-3148 [003] .... 52.435478: reclaim_retry_zone: node=0 zone=DMA32 order=0 reclaimable=51 available=11084 min_wmark=11084 no_progress_loops=7 wmark_check=0
mem_eater-3148 [003] .... 52.435478: reclaim_retry_zone: node=0 zone=DMA order=0 reclaimable=0 available=1126 min_wmark=179 no_progress_loops=7 wmark_check=0
The above shows that we can quickly deduce that the reclaim stopped
making any progress (see no_progress_loops increased in each round) and
while there were still some 51 reclaimable pages they couldn't be
dropped for some reason (vmscan trace points would tell us more about
that part). available will represent reclaimable + free_pages scaled
down per no_progress_loops factor. This is essentially an optimistic
estimate of how much memory we would have when reclaiming everything.
This can be compared to min_wmark to get a rought idea but the
wmark_check tells the result of the watermark check which is more
precise (includes lowmem reserves, considers the order etc.). As we can
see no zone is eligible in the end and that is why we have triggered the
oom in this situation.
Please note that higher order requests might fail on the wmark_check
even when there is much more memory available than min_wmark - e.g.
when the memory is fragmented. A follow up tracepoint will help to
debug those situations.
Link: http://lkml.kernel.org/r/20161220130135.15719-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
