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For ACKs generated inside the I/O thread, transmit the ACK at the point of
generation. Where the ACK is generated outside of the I/O thread, it's
offloaded to the I/O thread to transmit it.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Add a tracepoint to log when a cwnd reset occurs due to lack of
transmission on a call.
Add stat counters to count transmission underflows (ie. when we have tx
window space, but sendmsg doesn't manage to keep up), cwnd resets and
transmission failures.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Move the functions from the call->processor and local->processor work items
into the domain of the I/O thread.
The call event processor, now called from the I/O thread, then takes over
the job of cranking the call state machine, processing incoming packets and
transmitting DATA, ACK and ABORT packets. In a future patch,
rxrpc_send_ACK() will transmit the ACK on the spot rather than queuing it
for later transmission.
The call event processor becomes purely received-skb driven. It only
transmits things in response to events. We use "pokes" to queue a dummy
skb to make it do things like start/resume transmitting data. Timer expiry
also results in pokes.
The connection event processor, becomes similar, though crypto events, such
as dealing with CHALLENGE and RESPONSE packets is offloaded to a work item
to avoid doing crypto in the I/O thread.
The local event processor is removed and VERSION response packets are
generated directly from the packet parser. Similarly, ABORTs generated in
response to protocol errors will be transmitted immediately rather than
being pushed onto a queue for later transmission.
Changes:
========
ver #2)
- Fix a couple of introduced lock context imbalances.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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A received skbuff needs a ref when it gets put on a call data queue or conn
packet queue, and rxrpc_input_packet() and co. jump through a lot of hoops
to avoid double-dropping the skbuff ref so that we can avoid getting a ref
when we queue the packet.
Change this so that the skbuff ref is unconditionally dropped by the caller
of rxrpc_input_packet(). An additional ref is then taken on the packet if
it is pushed onto a queue.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Move DATA transmission into the call processor work item. In a future
patch, this will be called from the I/O thread rather than being itsown
work item.
This will allow DATA transmission to be driven directly by incoming ACKs,
pokes and timers as those are processed.
The Tx queue is also split: The queue of packets prepared by sendmsg is now
places in call->tx_sendmsg and the packet dispatcher decants the packets
into call->tx_buffer as space becomes available in the transmission
window. This allows sendmsg to run ahead of the available space to try and
prevent an underflow in transmission.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Copy client call parameters into rxrpc_call earlier so that that can be
used to convey them to the connection code - which can then be offloaded to
the I/O thread.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Provide a means by which an event notification can be sent to a call such
that the I/O thread can process it rather than it being done in a separate
workqueue. This will allow a lot of locking to be removed.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Currently, rxrpc gives the connection's work item a ref on the connection
when it queues it - and this is called from the timer expiration function.
The problem comes when queue_work() fails (ie. the work item is already
queued): the timer routine must put the ref - but this may cause the
cleanup code to run.
This has the unfortunate effect that the cleanup code may then be run in
softirq context - which means that any spinlocks it might need to touch
have to be guarded to disable softirqs (ie. they need a "_bh" suffix).
(1) Don't give a ref to the work item.
(2) Simplify handling of service connections by adding a separate active
count so that the refcount isn't also used for this.
(3) Connection destruction for both client and service connections can
then be cleaned up by putting rxrpc_put_connection() out of line and
making a tidy progression through the destruction code (offloaded to a
workqueue if put from softirq or processor function context). The RCU
part of the cleanup then only deals with the freeing at the end.
(4) Make rxrpc_queue_conn() return immediately if it sees the active count
is -1 rather then queuing the connection.
(5) Make sure that the cleanup routine waits for the work item to
complete.
(6) Stash the rxrpc_net pointer in the conn struct so that the rcu free
routine can use it, even if the local endpoint has been freed.
Unfortunately, neither the timer nor the work item can simply get around
the problem by just using refcount_inc_not_zero() as the waits would still
have to be done, and there would still be the possibility of having to put
the ref in the expiration function.
Note the connection work item is mostly going to go away with the main
event work being transferred to the I/O thread, so the wait in (6) will
become obsolete.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Currently, rxrpc gives the call timer a ref on the call when it starts it
and this is passed along to the workqueue by the timer expiration function.
The problem comes when queue_work() fails (ie. the work item is already
queued): the timer routine must put the ref - but this may cause the
cleanup code to run.
This has the unfortunate effect that the cleanup code may then be run in
softirq context - which means that any spinlocks it might need to touch
have to be guarded to disable softirqs (ie. they need a "_bh" suffix).
Fix this by:
(1) Don't give a ref to the timer.
(2) Making the expiration function not do anything if the refcount is 0.
Note that this is more of an optimisation.
(3) Make sure that the cleanup routine waits for timer to complete.
However, this has a consequence that timer cannot give a ref to the work
item. Therefore the following fixes are also necessary:
(4) Don't give a ref to the work item.
(5) Make the work item return asap if it sees the ref count is 0.
(6) Make sure that the cleanup routine waits for the work item to
complete.
Unfortunately, neither the timer nor the work item can simply get around
the problem by just using refcount_inc_not_zero() as the waits would still
have to be done, and there would still be the possibility of having to put
the ref in the expiration function.
Note the call work item is going to go away with the work being transferred
to the I/O thread, so the wait in (6) will become obsolete.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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In rxrpc tracing, use enums to generate lists of points of interest rather
than __builtin_return_address() for the sk_buff tracepoint.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Add a tracepoint for the rxrpc_bundle refcounting.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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In rxrpc tracing, use enums to generate lists of points of interest rather
than __builtin_return_address() for the rxrpc_call tracepoint
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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In rxrpc tracing, use enums to generate lists of points of interest rather
than __builtin_return_address() for the rxrpc_conn tracepoint
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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In rxrpc tracing, use enums to generate lists of points of interest rather
than __builtin_return_address() for the rxrpc_peer tracepoint
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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In rxrpc tracing, use enums to generate lists of points of interest rather
than __builtin_return_address() for the rxrpc_local tracepoint
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Remove the kproto() and _proto() debugging macros in preference to using
tracepoints for this.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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tools/lib/bpf/ringbuf.c
927cbb478adf ("libbpf: Handle size overflow for ringbuf mmap")
b486d19a0ab0 ("libbpf: checkpatch: Fixed code alignments in ringbuf.c")
https://lore.kernel.org/all/20221121122707.44d1446a@canb.auug.org.au/
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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For the cases where 'reason' doesn't give any clue, it's still
nice to be able to track the kfree_skb caller location. %p doesn't
help much so let's use %pS which prints the symbol+offset.
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20221123040947.1015721-1-sdf@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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filename from function call
Refactor the mm_khugepaged_scan_file tracepoint to move filename
dereference to the tracepoint definition, to maintain consistency with
other tracepoints[1].
[1]:lore.kernel.org/lkml/20221024111621.3ba17e2c@gandalf.local.home/
Link: https://lkml.kernel.org/r/20221026044524.54793-1-gautammenghani201@gmail.com
Fixes: d41fd2016ed07 ("mm/khugepaged: add tracepoint to hpage_collapse_scan_file()")
Signed-off-by: Gautam Menghani <gautammenghani201@gmail.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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rxrpc has a problem in its congestion management in that it saves the
congestion window size (cwnd) from one call to another, but if this is 0 at
the time is saved, then the next call may not actually manage to ever
transmit anything.
To this end:
(1) Don't save cwnd between calls, but rather reset back down to the
initial cwnd and re-enter slow-start if data transmission is idle for
more than an RTT.
(2) Preserve ssthresh instead, as that is a handy estimate of pipe
capacity. Knowing roughly when to stop slow start and enter
congestion avoidance can reduce the tendency to overshoot and drop
larger amounts of packets when probing.
In future, cwind growth also needs to be constrained when the window isn't
being filled due to being application limited.
Reported-by: Simon Wilkinson <sxw@auristor.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Improve the tracking of which packets need to be transmitted by saving the
last ACK packet that we receive that has a populated soft-ACK table rather
than marking packets. Then we can step through the soft-ACK table and look
at the packets we've transmitted beyond that to determine which packets we
might want to retransmit.
We also look at the highest serial number that has been acked to try and
guess which packets we've transmitted the peer is likely to have seen. If
necessary, we send a ping to retrieve that number.
One downside that might be a problem is that we can't then compare the
previous acked/unacked state so easily in rxrpc_input_soft_acks() - which
is a potential problem for the slow-start algorithm.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Change the way the Tx queueing works to make the following ends easier to
achieve:
(1) The filling of packets, the encryption of packets and the transmission
of packets can be handled in parallel by separate threads, rather than
rxrpc_sendmsg() allocating, filling, encrypting and transmitting each
packet before moving onto the next one.
(2) Get rid of the fixed-size ring which sets a hard limit on the number
of packets that can be retained in the ring. This allows the number
of packets to increase without having to allocate a very large ring or
having variable-sized rings.
[Note: the downside of this is that it's then less efficient to locate
a packet for retransmission as we then have to step through a list and
examine each buffer in the list.]
(3) Allow the filler/encrypter to run ahead of the transmission window.
(4) Make it easier to do zero copy UDP from the packet buffers.
(5) Make it easier to do zero copy from userspace to the packet buffers -
and thence to UDP (only if for unauthenticated connections).
To that end, the following changes are made:
(1) Use the new rxrpc_txbuf struct instead of sk_buff for keeping packets
to be transmitted in. This allows them to be placed on multiple
queues simultaneously. An sk_buff isn't really necessary as it's
never passed on to lower-level networking code.
(2) Keep the transmissable packets in a linked list on the call struct
rather than in a ring. As a consequence, the annotation buffer isn't
used either; rather a flag is set on the packet to indicate ackedness.
(3) Use the RXRPC_CALL_TX_LAST flag to indicate that the last packet to be
transmitted has been queued. Add RXRPC_CALL_TX_ALL_ACKED to indicate
that all packets up to and including the last got hard acked.
(4) Wire headers are now stored in the txbuf rather than being concocted
on the stack and they're stored immediately before the data, thereby
allowing zerocopy of a single span.
(5) Don't bother with instant-resend on transmission failure; rather,
leave it for a timer or an ACK packet to trigger.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Get rid of the Rx ring and replace it with a pair of queues instead. One
queue gets the packets that are in-sequence and are ready for processing by
recvmsg(); the other queue gets the out-of-sequence packets for addition to
the first queue as the holes get filled.
The annotation ring is removed and replaced with a SACK table. The SACK
table has the bits set that correspond exactly to the sequence number of
the packet being acked. The SACK ring is copied when an ACK packet is
being assembled and rotated so that the first ACK is in byte 0.
Flow control handling is altered so that packets that are moved to the
in-sequence queue are hard-ACK'd even before they're consumed - and then
the Rx window size in the ACK packet (rsize) is shrunk down to compensate
(even going to 0 if the window is full).
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Split up received jumbo packets into separate skbuffs by cloning the
original skbuff for each subpacket and setting the offset and length of the
data in that subpacket in the skbuff's private data. The subpackets are
then placed on the recvmsg queue separately. The security class then gets
to revise the offset and length to remove its metadata.
If we fail to clone a packet, we just drop it and let the peer resend it.
The original packet gets used for the final subpacket.
This should make it easier to handle parallel decryption of the subpackets.
It also simplifies the handling of lost or misordered packets in the
queuing/buffering loop as the possibility of overlapping jumbo packets no
longer needs to be considered.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Split the rxrpc_recvmsg tracepoint so that the tracepoints that are about
data packet processing (and which have extra pieces of information) are
separate from the tracepoint that shows the general flow of recvmsg().
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Clean up the rxrpc_propose_ACK() function. If deferred PING ACK proposal
is split out, it's only really needed for deferred DELAY ACKs. All other
ACKs, bar terminal IDLE ACK are sent immediately. The deferred IDLE ACK
submission can be handled by conversion of a DELAY ACK into an IDLE ACK if
there's nothing to be SACK'd.
Also, because there's a delay between an ACK being generated and being
transmitted, it's possible that other ACKs of the same type will be
generated during that interval. Apart from the ACK time and the serial
number responded to, most of the ACK body, including window and SACK
parameters, are not filled out till the point of transmission - so we can
avoid generating a new ACK if there's one pending that will cover the SACK
data we need to convey.
Therefore, don't propose a new DELAY or IDLE ACK for a call if there's one
already pending.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Allocate rxrpc_txbuf records for ACKs and put onto a queue for the
transmitter thread to dispatch.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Define a struct, rxrpc_txbuf, to carry data to be transmitted instead of a
socket buffer so that it can be placed onto multiple queues at once. This
also allows the data buffer to be in the same allocation as the internal
data.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Remove the flags from the rxrpc_skb tracepoint as we're no longer going to
be using this for the transmission buffers and so marking which are
transmission buffers isn't going to be necessary.
Note that this also remove the rxrpc skb flag that indicates if this is a
transmission buffer and so the count is not updated for the moment.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Record stats for why the REQUEST-ACK flag is being set.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Split the tracepoint for call timer-set to separate out the call
timer-expiration event
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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Add a tracepoint to log why the request-ack flag is set on an outgoing DATA
packet, allowing debugging as to why.
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
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git://www.linux-watchdog.org/linux-watchdog
Pull watchdog updates from Wim Van Sebroeck:
- Add tracing events for the most common watchdog events
* tag 'linux-watchdog-6.1-rc2' of git://www.linux-watchdog.org/linux-watchdog:
watchdog: Add tracing events for the most usual watchdog events
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To simplify debugging which process touches a watchdog and when, add
tracing events for .start(), .set_timeout(), .ping() and .stop().
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20221008174602.3972859-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs
Pull f2fs updates from Jaegeuk Kim:
"This round looks fairly small comparing to the previous updates and
includes mostly minor bug fixes. Nevertheless, as we've still
interested in improving the stability, Chao added some debugging
methods to diagnoze subtle runtime inconsistency problem.
Enhancements:
- store all the corruption or failure reasons in superblock
- detect meta inode, summary info, and block address inconsistency
- increase the limit for reserve_root for low-end devices
- add the number of compressed IO in iostat
Bug fixes:
- DIO write fix for zoned devices
- do out-of-place writes for cold files
- fix some stat updates (FS_CP_DATA_IO, dirty page count)
- fix race condition on setting FI_NO_EXTENT flag
- fix data races when freezing super
- fix wrong continue condition check in GC
- do not allow ATGC for LFS mode
In addition, there're some code enhancement and clean-ups as usual"
* tag 'f2fs-for-6.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/jaegeuk/f2fs: (32 commits)
f2fs: change to use atomic_t type form sbi.atomic_files
f2fs: account swapfile inodes
f2fs: allow direct read for zoned device
f2fs: support recording errors into superblock
f2fs: support recording stop_checkpoint reason into super_block
f2fs: remove the unnecessary check in f2fs_xattr_fiemap
f2fs: introduce cp_status sysfs entry
f2fs: fix to detect corrupted meta ino
f2fs: fix to account FS_CP_DATA_IO correctly
f2fs: code clean and fix a type error
f2fs: add "c_len" into trace_f2fs_update_extent_tree_range for compressed file
f2fs: fix to do sanity check on summary info
f2fs: port to vfs{g,u}id_t and associated helpers
f2fs: fix to do sanity check on destination blkaddr during recovery
f2fs: let FI_OPU_WRITE override FADVISE_COLD_BIT
f2fs: fix race condition on setting FI_NO_EXTENT flag
f2fs: remove redundant check in f2fs_sanity_check_cluster
f2fs: add static init_idisk_time function to reduce the code
f2fs: fix typo
f2fs: fix wrong dirty page count when race between mmap and fallocate.
...
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- Yu Zhao's Multi-Gen LRU patches are here. They've been under test in
linux-next for a couple of months without, to my knowledge, any
negative reports (or any positive ones, come to that).
- Also the Maple Tree from Liam Howlett. An overlapping range-based
tree for vmas. It it apparently slightly more efficient in its own
right, but is mainly targeted at enabling work to reduce mmap_lock
contention.
Liam has identified a number of other tree users in the kernel which
could be beneficially onverted to mapletrees.
Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat
at [1]. This has yet to be addressed due to Liam's unfortunately
timed vacation. He is now back and we'll get this fixed up.
- Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses
clang-generated instrumentation to detect used-unintialized bugs down
to the single bit level.
KMSAN keeps finding bugs. New ones, as well as the legacy ones.
- Yang Shi adds a userspace mechanism (madvise) to induce a collapse of
memory into THPs.
- Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to
support file/shmem-backed pages.
- userfaultfd updates from Axel Rasmussen
- zsmalloc cleanups from Alexey Romanov
- cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and
memory-failure
- Huang Ying adds enhancements to NUMA balancing memory tiering mode's
page promotion, with a new way of detecting hot pages.
- memcg updates from Shakeel Butt: charging optimizations and reduced
memory consumption.
- memcg cleanups from Kairui Song.
- memcg fixes and cleanups from Johannes Weiner.
- Vishal Moola provides more folio conversions
- Zhang Yi removed ll_rw_block() :(
- migration enhancements from Peter Xu
- migration error-path bugfixes from Huang Ying
- Aneesh Kumar added ability for a device driver to alter the memory
tiering promotion paths. For optimizations by PMEM drivers, DRM
drivers, etc.
- vma merging improvements from Jakub Matěn.
- NUMA hinting cleanups from David Hildenbrand.
- xu xin added aditional userspace visibility into KSM merging
activity.
- THP & KSM code consolidation from Qi Zheng.
- more folio work from Matthew Wilcox.
- KASAN updates from Andrey Konovalov.
- DAMON cleanups from Kaixu Xia.
- DAMON work from SeongJae Park: fixes, cleanups.
- hugetlb sysfs cleanups from Muchun Song.
- Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core.
Link: https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com [1]
* tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (555 commits)
hugetlb: allocate vma lock for all sharable vmas
hugetlb: take hugetlb vma_lock when clearing vma_lock->vma pointer
hugetlb: fix vma lock handling during split vma and range unmapping
mglru: mm/vmscan.c: fix imprecise comments
mm/mglru: don't sync disk for each aging cycle
mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol
mm: memcontrol: use do_memsw_account() in a few more places
mm: memcontrol: deprecate swapaccounting=0 mode
mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled
mm/secretmem: remove reduntant return value
mm/hugetlb: add available_huge_pages() func
mm: remove unused inline functions from include/linux/mm_inline.h
selftests/vm: add selftest for MADV_COLLAPSE of uffd-minor memory
selftests/vm: add file/shmem MADV_COLLAPSE selftest for cleared pmd
selftests/vm: add thp collapse shmem testing
selftests/vm: add thp collapse file and tmpfs testing
selftests/vm: modularize thp collapse memory operations
selftests/vm: dedup THP helpers
mm/khugepaged: add tracepoint to hpage_collapse_scan_file()
mm/madvise: add file and shmem support to MADV_COLLAPSE
...
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git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab
Pull slab fixes from Vlastimil Babka:
- The "common kmalloc v4" series [1] by Hyeonggon Yoo.
While the plan after LPC is to try again if it's possible to get rid
of SLOB and SLAB (and if any critical aspect of those is not possible
to achieve with SLUB today, modify it accordingly), it will take a
while even in case there are no objections.
Meanwhile this is a nice cleanup and some parts (e.g. to the
tracepoints) will be useful even if we end up with a single slab
implementation in the future:
- Improves the mm/slab_common.c wrappers to allow deleting
duplicated code between SLAB and SLUB.
- Large kmalloc() allocations in SLAB are passed to page allocator
like in SLUB, reducing number of kmalloc caches.
- Removes the {kmem_cache_alloc,kmalloc}_node variants of
tracepoints, node id parameter added to non-_node variants.
- Addition of kmalloc_size_roundup()
The first two patches from a series by Kees Cook [2] that introduce
kmalloc_size_roundup(). This will allow merging of per-subsystem
patches using the new function and ultimately stop (ab)using ksize()
in a way that causes ongoing trouble for debugging functionality and
static checkers.
- Wasted kmalloc() memory tracking in debugfs alloc_traces
A patch from Feng Tang that enhances the existing debugfs
alloc_traces file for kmalloc caches with information about how much
space is wasted by allocations that needs less space than the
particular kmalloc cache provides.
- My series [3] to fix validation races for caches with enabled
debugging:
- By decoupling the debug cache operation more from non-debug
fastpaths, extra locking simplifications were possible and thus
done afterwards.
- Additional cleanup of PREEMPT_RT specific code on top, by Thomas
Gleixner.
- A late fix for slab page leaks caused by the series, by Feng
Tang.
- Smaller fixes and cleanups:
- Unneeded variable removals, by ye xingchen
- A cleanup removing a BUG_ON() in create_unique_id(), by Chao Yu
Link: https://lore.kernel.org/all/20220817101826.236819-1-42.hyeyoo@gmail.com/ [1]
Link: https://lore.kernel.org/all/20220923202822.2667581-1-keescook@chromium.org/ [2]
Link: https://lore.kernel.org/all/20220823170400.26546-1-vbabka@suse.cz/ [3]
* tag 'slab-for-6.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab: (30 commits)
mm/slub: fix a slab missed to be freed problem
slab: Introduce kmalloc_size_roundup()
slab: Remove __malloc attribute from realloc functions
mm/slub: clean up create_unique_id()
mm/slub: enable debugging memory wasting of kmalloc
slub: Make PREEMPT_RT support less convoluted
mm/slub: simplify __cmpxchg_double_slab() and slab_[un]lock()
mm/slub: convert object_map_lock to non-raw spinlock
mm/slub: remove slab_lock() usage for debug operations
mm/slub: restrict sysfs validation to debug caches and make it safe
mm/sl[au]b: check if large object is valid in __ksize()
mm/slab_common: move declaration of __ksize() to mm/slab.h
mm/slab_common: drop kmem_alloc & avoid dereferencing fields when not using
mm/slab_common: unify NUMA and UMA version of tracepoints
mm/sl[au]b: cleanup kmem_cache_alloc[_node]_trace()
mm/sl[au]b: generalize kmalloc subsystem
mm/slub: move free_debug_processing() further
mm/sl[au]b: introduce common alloc/free functions without tracepoint
mm/slab: kmalloc: pass requests larger than order-1 page to page allocator
mm/slab_common: cleanup kmalloc_large()
...
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc
Pull char/misc and other driver updates from Greg KH:
"Here is the large set of char/misc and other small driver subsystem
changes for 6.1-rc1. Loads of different things in here:
- IIO driver updates, additions, and changes. Probably the largest
part of the diffstat
- habanalabs driver update with support for new hardware and
features, the second largest part of the diff.
- fpga subsystem driver updates and additions
- mhi subsystem updates
- Coresight driver updates
- gnss subsystem updates
- extcon driver updates
- icc subsystem updates
- fsi subsystem updates
- nvmem subsystem and driver updates
- misc driver updates
- speakup driver additions for new features
- lots of tiny driver updates and cleanups
All of these have been in the linux-next tree for a while with no
reported issues"
* tag 'char-misc-6.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/char-misc: (411 commits)
w1: Split memcpy() of struct cn_msg flexible array
spmi: pmic-arb: increase SPMI transaction timeout delay
spmi: pmic-arb: block access for invalid PMIC arbiter v5 SPMI writes
spmi: pmic-arb: correct duplicate APID to PPID mapping logic
spmi: pmic-arb: add support to dispatch interrupt based on IRQ status
spmi: pmic-arb: check apid against limits before calling irq handler
spmi: pmic-arb: do not ack and clear peripheral interrupts in cleanup_irq
spmi: pmic-arb: handle spurious interrupt
spmi: pmic-arb: add a print in cleanup_irq
drivers: spmi: Directly use ida_alloc()/free()
MAINTAINERS: add TI ECAP driver info
counter: ti-ecap-capture: capture driver support for ECAP
Documentation: ABI: sysfs-bus-counter: add frequency & num_overflows items
dt-bindings: counter: add ti,am62-ecap-capture.yaml
counter: Introduce the COUNTER_COMP_ARRAY component type
counter: Consolidate Counter extension sysfs attribute creation
counter: Introduce the Count capture component
counter: 104-quad-8: Add Signal polarity component
counter: Introduce the Signal polarity component
counter: interrupt-cnt: Implement watch_validate callback
...
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Pull io_uring updates from Jens Axboe:
- Add supported for more directly managed task_work running.
This is beneficial for real world applications that end up issuing
lots of system calls as part of handling work. Normal task_work will
always execute as we transition in and out of the kernel, even for
"unrelated" system calls. It's more efficient to defer the handling
of io_uring's deferred work until the application wants it to be run,
generally in batches.
As part of ongoing work to write an io_uring network backend for
Thrift, this has been shown to greatly improve performance. (Dylan)
- Add IOPOLL support for passthrough (Kanchan)
- Improvements and fixes to the send zero-copy support (Pavel)
- Partial IO handling fixes (Pavel)
- CQE ordering fixes around CQ ring overflow (Pavel)
- Support sendto() for non-zc as well (Pavel)
- Support sendmsg for zerocopy (Pavel)
- Networking iov_iter fix (Stefan)
- Misc fixes and cleanups (Pavel, me)
* tag 'for-6.1/io_uring-2022-10-03' of git://git.kernel.dk/linux: (56 commits)
io_uring/net: fix notif cqe reordering
io_uring/net: don't update msg_name if not provided
io_uring: don't gate task_work run on TIF_NOTIFY_SIGNAL
io_uring/rw: defer fsnotify calls to task context
io_uring/net: fix fast_iov assignment in io_setup_async_msg()
io_uring/net: fix non-zc send with address
io_uring/net: don't skip notifs for failed requests
io_uring/rw: don't lose short results on io_setup_async_rw()
io_uring/rw: fix unexpected link breakage
io_uring/net: fix cleanup double free free_iov init
io_uring: fix CQE reordering
io_uring/net: fix UAF in io_sendrecv_fail()
selftest/net: adjust io_uring sendzc notif handling
io_uring: ensure local task_work marks task as running
io_uring/net: zerocopy sendmsg
io_uring/net: combine fail handlers
io_uring/net: rename io_sendzc()
io_uring/net: support non-zerocopy sendto
io_uring/net: refactor io_setup_async_addr
io_uring/net: don't lose partial send_zc on fail
...
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git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux
Pull btrfs updates from David Sterba:
"There's a bunch of performance improvements, most notably the FIEMAP
speedup, the new block group tree to speed up mount on large
filesystems, more io_uring integration, some sysfs exports and the
usual fixes and core updates.
Summary:
Performance:
- outstanding FIEMAP speed improvement
- algorithmic change how extents are enumerated leads to orders of
magnitude speed boost (uncached and cached)
- extent sharing check speedup (2.2x uncached, 3x cached)
- add more cancellation points, allowing to interrupt seeking in
files with large number of extents
- more efficient hole and data seeking (4x uncached, 1.3x cached)
- sample results:
256M, 32K extents: 4s -> 29ms (~150x)
512M, 64K extents: 30s -> 59ms (~550x)
1G, 128K extents: 225s -> 120ms (~1800x)
- improved inode logging, especially for directories (on dbench
workload throughput +25%, max latency -21%)
- improved buffered IO, remove redundant extent state tracking,
lowering memory consumption and avoiding rb tree traversal
- add sysfs tunable to let qgroup temporarily skip exact accounting
when deleting snapshot, leading to a speedup but requiring a rescan
after that, will be used by snapper
- support io_uring and buffered writes, until now it was just for
direct IO, with the no-wait semantics implemented in the buffered
write path it now works and leads to speed improvement in IOPS
(2x), throughput (2.2x), latency (depends, 2x to 150x)
- small performance improvements when dropping and searching for
extent maps as well as when flushing delalloc in COW mode
(throughput +5MB/s)
User visible changes:
- new incompatible feature block-group-tree adding a dedicated tree
for tracking block groups, this allows a much faster load during
mount and avoids seeking unlike when it's scattered in the extent
tree items
- this reduces mount time for many-terabyte sized filesystems
- conversion tool will be provided so existing filesystem can also
be updated in place
- to reduce test matrix and feature combinations requires no-holes
and free-space-tree (mkfs defaults since 5.15)
- improved reporting of super block corruption detected by scrub
- scrub also tries to repair super block and does not wait until next
commit
- discard stats and tunables are exported in sysfs
(/sys/fs/btrfs/FSID/discard)
- qgroup status is exported in sysfs
(/sys/sys/fs/btrfs/FSID/qgroups/)
- verify that super block was not modified when thawing filesystem
Fixes:
- FIEMAP fixes
- fix extent sharing status, does not depend on the cached status
where merged
- flush delalloc so compressed extents are reported correctly
- fix alignment of VMA for memory mapped files on THP
- send: fix failures when processing inodes with no links (orphan
files and directories)
- fix race between quota enable and quota rescan ioctl
- handle more corner cases for read-only compat feature verification
- fix missed extent on fsync after dropping extent maps
Core:
- lockdep annotations to validate various transactions states and
state transitions
- preliminary support for fs-verity in send
- more effective memory use in scrub for subpage where sector is
smaller than page
- block group caching progress logic has been removed, load is now
synchronous
- simplify end IO callbacks and bio handling, use chained bios
instead of own tracking
- add no-wait semantics to several functions (tree search, nocow,
flushing, buffered write
- cleanups and refactoring
MM changes:
- export balance_dirty_pages_ratelimited_flags"
* tag 'for-6.1-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux: (177 commits)
btrfs: set generation before calling btrfs_clean_tree_block in btrfs_init_new_buffer
btrfs: drop extent map range more efficiently
btrfs: avoid pointless extent map tree search when flushing delalloc
btrfs: remove unnecessary next extent map search
btrfs: remove unnecessary NULL pointer checks when searching extent maps
btrfs: assert tree is locked when clearing extent map from logging
btrfs: remove unnecessary extent map initializations
btrfs: remove the refcount warning/check at free_extent_map()
btrfs: add helper to replace extent map range with a new extent map
btrfs: move open coded extent map tree deletion out of inode eviction
btrfs: use cond_resched_rwlock_write() during inode eviction
btrfs: use extent_map_end() at btrfs_drop_extent_map_range()
btrfs: move btrfs_drop_extent_cache() to extent_map.c
btrfs: fix missed extent on fsync after dropping extent maps
btrfs: remove stale prototype of btrfs_write_inode
btrfs: enable nowait async buffered writes
btrfs: assert nowait mode is not used for some btree search functions
btrfs: make btrfs_buffered_write nowait compatible
btrfs: plumb NOWAIT through the write path
btrfs: make lock_and_cleanup_extent_if_need nowait compatible
...
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git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound
Pull sound updates from Takashi Iwai:
"The majority of changes are ASoC drivers (SOF, Intel, AMD, Mediatek,
Qualcomm, TI, Apple Silicon, etc), while we see a few small fixes in
ALSA / ASoC core side, too.
Here are highlights:
Core:
- A new string helper parse_int_array_user() and cleanups with it
- Continued cleanup of memory allocation helpers
- PCM core optimization and hardening
- Continued ASoC core code cleanups
ASoC:
- Improvements to the SOF IPC4 code, especially around trace
- Support for AMD Rembrant DSPs, AMD Pink Sardine ACP 6.2, Apple
Silicon systems, Everest ES8326, Intel Sky Lake and Kaby Lake,
Mediatek MT8186 support, NXP i.MX8ULP DSPs, Qualcomm SC8280XP,
SM8250 and SM8450 and Texas Instruments SRC4392
HD- and USB-audio:
- Cleanups for unification of hda-ext bus
- HD-audio HDMI codec driver cleanups
- Continued endpoint management fixes for USB-audio
- New quirks as usual"
* tag 'sound-6.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound: (422 commits)
ALSA: hda: Fix position reporting on Poulsbo
ALSA: hda/hdmi: Don't skip notification handling during PM operation
ASoC: rockchip: i2s: use regmap_read_poll_timeout_atomic to poll I2S_CLR
ASoC: dt-bindings: Document audio OF graph dai-tdm-slot-num dai-tdm-slot-width props
ASoC: qcom: fix unmet direct dependencies for SND_SOC_QDSP6
ALSA: usb-audio: Fix potential memory leaks
ALSA: usb-audio: Fix NULL dererence at error path
ASoC: mediatek: mt8192-mt6359: Set the driver name for the card
ALSA: hda/realtek: More robust component matching for CS35L41
ASoC: Intel: sof_rt5682: remove SOF_RT1015_SPEAKER_AMP_100FS flag
ASoC: nau8825: Add TDM support
ASoC: core: clarify the driver name initialization
ASoC: mt6660: Fix PM disable depth imbalance in mt6660_i2c_probe
ASoC: wm5102: Fix PM disable depth imbalance in wm5102_probe
ASoC: wm5110: Fix PM disable depth imbalance in wm5110_probe
ASoC: wm8997: Fix PM disable depth imbalance in wm8997_probe
ASoC: wcd-mbhc-v2: Revert "ASoC: wcd-mbhc-v2: use pm_runtime_resume_and_get()"
ASoC: mediatek: mt8186: Fix spelling mistake "slect" -> "select"
ALSA: hda/realtek: Add quirk for HP Zbook Firefly 14 G9 model
ALSA: asihpi - Remove unused struct hpi_subsys_response
...
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The trace_f2fs_update_extent_tree_range could not record compressed
block length in the cluster of compress file and we just add it.
Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com>
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/teigland/linux-dlm
Pull dlm updates from David Teigland:
- Fix a couple races found with a new torture test
- Improve errors when api functions are used incorrectly
- Improve tracing for lock requests from user space
- Fix use after free in recently added tracing cod.
- Small internal code cleanups
* tag 'dlm-6.1' of git://git.kernel.org/pub/scm/linux/kernel/git/teigland/linux-dlm:
fs: dlm: fix possible use after free if tracing
fs: dlm: const void resource name parameter
fs: dlm: LSFL_CB_DELAY only for kernel lockspaces
fs: dlm: remove DLM_LSFL_FS from uapi
fs: dlm: trace user space callbacks
fs: dlm: change ls_clear_proc_locks to spinlock
fs: dlm: remove dlm_del_ast prototype
fs: dlm: handle rcom in else if branch
fs: dlm: allow lockspaces have zero lvblen
fs: dlm: fix invalid derefence of sb_lvbptr
fs: dlm: handle -EINVAL as log_error()
fs: dlm: use __func__ for function name
fs: dlm: handle -EBUSY first in unlock validation
fs: dlm: handle -EBUSY first in lock arg validation
fs: dlm: fix race between test_bit() and queue_work()
fs: dlm: fix race in lowcomms
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git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs
Pull erofs updates from Gao Xiang:
"In this cycle, for container use cases, fscache-based shared domain is
introduced [1] so that data blobs in the same domain will be storage
deduplicated and it will also be used for page cache sharing later.
Also, a special packed inode is now introduced to record inode
fragments which keep the tail part of files by Yue Hu [2]. You can
keep arbitary length or (at will) the whole file as a fragment and
then fragments can be optionally compressed in the packed inode
together and even deduplicated for smaller image sizes.
In addition to that, global compressed data deduplication by sharing
partial-referenced pclusters is also supported in this cycle.
Summary:
- Introduce fscache-based domain to share blobs between images
- Support recording fragments in a special packed inode
- Support partial-referenced pclusters for global compressed data
deduplication
- Fix an order >= MAX_ORDER warning due to crafted negative i_size
- Several cleanups"
Link: https://lore.kernel.org/r/20220916085940.89392-1-zhujia.zj@bytedance.com [1]
Link: https://lore.kernel.org/r/cover.1663065968.git.huyue2@coolpad.com [2]
* tag 'erofs-for-6.1-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs:
erofs: clean up erofs_iget()
erofs: clean up unnecessary code and comments
erofs: fold in z_erofs_reload_indexes()
erofs: introduce partial-referenced pclusters
erofs: support on-disk compressed fragments data
erofs: support interlaced uncompressed data for compressed files
erofs: clean up .read_folio() and .readahead() in fscache mode
erofs: introduce 'domain_id' mount option
erofs: Support sharing cookies in the same domain
erofs: introduce a pseudo mnt to manage shared cookies
erofs: introduce fscache-based domain
erofs: code clean up for fscache
erofs: use kill_anon_super() to kill super in fscache mode
erofs: fix order >= MAX_ORDER warning due to crafted negative i_size
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Add huge_memory:trace_mm_khugepaged_scan_file tracepoint to
hpage_collapse_scan_file() analogously to hpage_collapse_scan_pmd().
While this change is targeted at debugging MADV_COLLAPSE pathway, the
"mm_khugepaged" prefix is retained for symmetry with
huge_memory:trace_mm_khugepaged_scan_pmd, which retains it's legacy name
to prevent changing kernel ABI as much as possible.
Link: https://lkml.kernel.org/r/20220907144521.3115321-5-zokeefe@google.com
Link: https://lkml.kernel.org/r/20220922224046.1143204-5-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Add support for MADV_COLLAPSE to collapse shmem-backed and file-backed
memory into THPs (requires CONFIG_READ_ONLY_THP_FOR_FS=y).
On success, the backing memory will be a hugepage. For the memory range
and process provided, the page tables will synchronously have a huge pmd
installed, mapping the THP. Other mappings of the file extent mapped by
the memory range may be added to a set of entries that khugepaged will
later process and attempt update their page tables to map the THP by a
pmd.
This functionality unlocks two important uses:
(1) Immediately back executable text by THPs. Current support provided
by CONFIG_READ_ONLY_THP_FOR_FS may take a long time on a large
system which might impair services from serving at their full rated
load after (re)starting. Tricks like mremap(2)'ing text onto
anonymous memory to immediately realize iTLB performance prevents
page sharing and demand paging, both of which increase steady state
memory footprint. Now, we can have the best of both worlds: Peak
upfront performance and lower RAM footprints.
(2) userfaultfd-based live migration of virtual machines satisfy UFFD
faults by fetching native-sized pages over the network (to avoid
latency of transferring an entire hugepage). However, after guest
memory has been fully copied to the new host, MADV_COLLAPSE can
be used to immediately increase guest performance.
Since khugepaged is single threaded, this change now introduces
possibility of collapse contexts racing in file collapse path. There a
important few places to consider:
(1) hpage_collapse_scan_file(), when we xas_pause() and drop RCU.
We could have the memory collapsed out from under us, but
the next xas_for_each() iteration will correctly pick up the
hugepage. The hugepage might not be up to date (insofar as
copying of small page contents might not have completed - the
page still may be locked), but regardless what small page index
we were iterating over, we'll find the hugepage and identify it
as a suitably aligned compound page of order HPAGE_PMD_ORDER.
In khugepaged path, we locklessly check the value of the pmd,
and only add it to deferred collapse array if we find pmd
mapping pte table. This is fine, since other values that could
have raced in right afterwards denote failure, or that the
memory was successfully collapsed, so we don't need further
processing.
In madvise path, we'll take mmap_lock() in write to serialize
against page table updates and will know what to do based on the
true value of the pmd: recheck all ptes if we point to a pte table,
directly install the pmd, if the pmd has been cleared, but
memory not yet faulted, or nothing at all if we find a huge pmd.
It's worth putting emphasis here on how we treat the none pmd
here. If khugepaged has processed this mm's page tables
already, it will have left the pmd cleared (ready for refault by
the process). Depending on the VMA flags and sysfs settings,
amount of RAM on the machine, and the current load, could be a
relatively common occurrence - and as such is one we'd like to
handle successfully in MADV_COLLAPSE. When we see the none pmd
in collapse_pte_mapped_thp(), we've locked mmap_lock in write
and checked (a) huepaged_vma_check() to see if the backing
memory is appropriate still, along with VMA sizing and
appropriate hugepage alignment within the file, and (b) we've
found a hugepage head of order HPAGE_PMD_ORDER at the offset
in the file mapped by our hugepage-aligned virtual address.
Even though the common-case is likely race with khugepaged,
given these checks (regardless how we got here - we could be
operating on a completely different file than originally checked
in hpage_collapse_scan_file() for all we know) it should be safe
to directly make the pmd a huge pmd pointing to this hugepage.
(2) collapse_file() is mostly serialized on the same file extent by
lock sequence:
| lock hupepage
| lock mapping->i_pages
| lock 1st page
| unlock mapping->i_pages
| <page checks>
| lock mapping->i_pages
| page_ref_freeze(3)
| xas_store(hugepage)
| unlock mapping->i_pages
| page_ref_unfreeze(1)
| unlock 1st page
V unlock hugepage
Once a context (who already has their fresh hugepage locked)
locks mapping->i_pages exclusively, it will hold said lock
until it locks the first page, and it will hold that lock until
the after the hugepage has been added to the page cache (and
will unlock the hugepage after page table update, though that
isn't important here).
A racing context that loses the race for mapping->i_pages will
then lose the race to locking the first page. Here - depending
on how far the other racing context has gotten - we might find
the new hugepage (in which case we'll exit cleanly when we
check PageTransCompound()), or we'll find the "old" 1st small
page (in which we'll exit cleanly when we discover unexpected
refcount of 2 after isolate_lru_page()). This is assuming we
are able to successfully lock the page we find - in shmem path,
we could just fail the trylock and exit cleanly anyways.
Failure path in collapse_file() is similar: once we hold lock
on 1st small page, we are serialized against other collapse
contexts. Before the 1st small page is unlocked, we add it
back to the pagecache and unfreeze the refcount appropriately.
Contexts who lost the race to the 1st small page will then find
the same 1st small page with the correct refcount and will be
able to proceed.
[zokeefe@google.com: don't check pmd value twice in collapse_pte_mapped_thp()]
Link: https://lkml.kernel.org/r/20220927033854.477018-1-zokeefe@google.com
[shy828301@gmail.com: Delete hugepage_vma_revalidate_anon(), remove
check for multi-add in khugepaged_add_pte_mapped_thp()]
Link: https://lore.kernel.org/linux-mm/CAHbLzkrtpM=ic7cYAHcqkubah5VTR8N5=k5RT8MTvv5rN1Y91w@mail.gmail.com/
Link: https://lkml.kernel.org/r/20220907144521.3115321-4-zokeefe@google.com
Link: https://lkml.kernel.org/r/20220922224046.1143204-4-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The main benefit of THPs are that they can be mapped at the pmd level,
increasing the likelihood of TLB hit and spending less cycles in page
table walks. pte-mapped hugepages - that is - hugepage-aligned compound
pages of order HPAGE_PMD_ORDER mapped by ptes - although being contiguous
in physical memory, don't have this advantage. In fact, one could argue
they are detrimental to system performance overall since they occupy a
precious hugepage-aligned/sized region of physical memory that could
otherwise be used more effectively. Additionally, pte-mapped hugepages
can be the cheapest memory to collapse for khugepaged since no new
hugepage allocation or copying of memory contents is necessary - we only
need to update the mapping page tables.
In the anonymous collapse path, we are able to collapse pte-mapped
hugepages (albeit, perhaps suboptimally), but the file/shmem path makes no
effort when compound pages (of any order) are encountered.
Identify pte-mapped hugepages in the file/shmem collapse path. The
final step of which makes a racy check of the value of the pmd to
ensure it maps a pte table. This should be fine, since races that
result in false-positive (i.e. attempt collapse even though we
shouldn't) will fail later in collapse_pte_mapped_thp() once we
actually lock mmap_lock and reinspect the pmd value. Races that result
in false-negatives (i.e. where we decide to not attempt collapse, but
should have) shouldn't be an issue, since in the worst case, we do
nothing - which is what we've done up to this point. We make a similar
check in retract_page_tables(). If we do think we've found a
pte-mapped hugepgae in khugepaged context, attempt to update page
tables mapping this hugepage.
Note that these collapses still count towards the
/sys/kernel/mm/transparent_hugepage/khugepaged/pages_collapsed counter,
and if the pte-mapped hugepage was also mapped into multiple process'
address spaces, could be incremented for each page table update. Since we
increment the counter when a pte-mapped hugepage is successfully added to
the list of to-collapse pte-mapped THPs, it's possible that we never
actually update the page table either. This is different from how
file/shmem pages_collapsed accounting works today where only a successful
page cache update is counted (it's also possible here that no page tables
are actually changed). Though it incurs some slop, this is preferred to
either not accounting for the event at all, or plumbing through data in
struct mm_slot on whether to account for the collapse or not.
Also note that work still needs to be done to support arbitrary compound
pages, and that this should all be converted to using folios.
[shy828301@gmail.com: Spelling mistake, update comment, and add Documentation]
Link: https://lore.kernel.org/linux-mm/CAHbLzkpHwZxFzjfX9nxVoRhzup8WMjMfyL6Xiq8mZ9M-N3ombw@mail.gmail.com/
Link: https://lkml.kernel.org/r/20220907144521.3115321-3-zokeefe@google.com
Link: https://lkml.kernel.org/r/20220922224046.1143204-3-zokeefe@google.com
Signed-off-by: Zach O'Keefe <zokeefe@google.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Chris Kennelly <ckennelly@google.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: James Houghton <jthoughton@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rongwei Wang <rongwei.wang@linux.alibaba.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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isdir indicated REQ_META|REQ_PRIO which no longer works now.
Get rid of isdir entirely.
Link: https://lore.kernel.org/r/20220927063607.54832-2-hsiangkao@linux.alibaba.com
Reviewed-by: Yue Hu <huyue2@coolpad.com>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
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Start tracking the VMAs with the new maple tree structure in parallel with
the rb_tree. Add debug and trace events for maple tree operations and
duplicate the rb_tree that is created on forks into the maple tree.
The maple tree is added to the mm_struct including the mm_init struct,
added support in required mm/mmap functions, added tracking in kernel/fork
for process forking, and used to find the unmapped_area and checked
against what the rbtree finds.
This also moves the mmap_lock() in exit_mmap() since the oom reaper call
does walk the VMAs. Otherwise lockdep will be unhappy if oom happens.
When splitting a vma fails due to allocations of the maple tree nodes,
the error path in __split_vma() calls new->vm_ops->close(new). The page
accounting for hugetlb is actually in the close() operation, so it
accounts for the removal of 1/2 of the VMA which was not adjusted. This
results in a negative exit value. To avoid the negative charge, set
vm_start = vm_end and vm_pgoff = 0.
There is also a potential accounting issue in special mappings from
insert_vm_struct() failing to allocate, so reverse the charge there in
the failure scenario.
Link: https://lkml.kernel.org/r/20220906194824.2110408-9-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Tested-by: Yu Zhao <yuzhao@google.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: SeongJae Park <sj@kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "Introducing the Maple Tree"
The maple tree is an RCU-safe range based B-tree designed to use modern
processor cache efficiently. There are a number of places in the kernel
that a non-overlapping range-based tree would be beneficial, especially
one with a simple interface. If you use an rbtree with other data
structures to improve performance or an interval tree to track
non-overlapping ranges, then this is for you.
The tree has a branching factor of 10 for non-leaf nodes and 16 for leaf
nodes. With the increased branching factor, it is significantly shorter
than the rbtree so it has fewer cache misses. The removal of the linked
list between subsequent entries also reduces the cache misses and the need
to pull in the previous and next VMA during many tree alterations.
The first user that is covered in this patch set is the vm_area_struct,
where three data structures are replaced by the maple tree: the augmented
rbtree, the vma cache, and the linked list of VMAs in the mm_struct. The
long term goal is to reduce or remove the mmap_lock contention.
The plan is to get to the point where we use the maple tree in RCU mode.
Readers will not block for writers. A single write operation will be
allowed at a time. A reader re-walks if stale data is encountered. VMAs
would be RCU enabled and this mode would be entered once multiple tasks
are using the mm_struct.
Davidlor said
: Yes I like the maple tree, and at this stage I don't think we can ask for
: more from this series wrt the MM - albeit there seems to still be some
: folks reporting breakage. Fundamentally I see Liam's work to (re)move
: complexity out of the MM (not to say that the actual maple tree is not
: complex) by consolidating the three complimentary data structures very
: much worth it considering performance does not take a hit. This was very
: much a turn off with the range locking approach, which worst case scenario
: incurred in prohibitive overhead. Also as Liam and Matthew have
: mentioned, RCU opens up a lot of nice performance opportunities, and in
: addition academia[1] has shown outstanding scalability of address spaces
: with the foundation of replacing the locked rbtree with RCU aware trees.
A similar work has been discovered in the academic press
https://pdos.csail.mit.edu/papers/rcuvm:asplos12.pdf
Sheer coincidence. We designed our tree with the intention of solving the
hardest problem first. Upon settling on a b-tree variant and a rough
outline, we researched ranged based b-trees and RCU b-trees and did find
that article. So it was nice to find reassurances that we were on the
right path, but our design choice of using ranges made that paper unusable
for us.
This patch (of 70):
The maple tree is an RCU-safe range based B-tree designed to use modern
processor cache efficiently. There are a number of places in the kernel
that a non-overlapping range-based tree would be beneficial, especially
one with a simple interface. If you use an rbtree with other data
structures to improve performance or an interval tree to track
non-overlapping ranges, then this is for you.
The tree has a branching factor of 10 for non-leaf nodes and 16 for leaf
nodes. With the increased branching factor, it is significantly shorter
than the rbtree so it has fewer cache misses. The removal of the linked
list between subsequent entries also reduces the cache misses and the need
to pull in the previous and next VMA during many tree alterations.
The first user that is covered in this patch set is the vm_area_struct,
where three data structures are replaced by the maple tree: the augmented
rbtree, the vma cache, and the linked list of VMAs in the mm_struct. The
long term goal is to reduce or remove the mmap_lock contention.
The plan is to get to the point where we use the maple tree in RCU mode.
Readers will not block for writers. A single write operation will be
allowed at a time. A reader re-walks if stale data is encountered. VMAs
would be RCU enabled and this mode would be entered once multiple tasks
are using the mm_struct.
There is additional BUG_ON() calls added within the tree, most of which
are in debug code. These will be replaced with a WARN_ON() call in the
future. There is also additional BUG_ON() calls within the code which
will also be reduced in number at a later date. These exist to catch
things such as out-of-range accesses which would crash anyways.
Link: https://lkml.kernel.org/r/20220906194824.2110408-1-Liam.Howlett@oracle.com
Link: https://lkml.kernel.org/r/20220906194824.2110408-2-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Tested-by: David Howells <dhowells@redhat.com>
Tested-by: Sven Schnelle <svens@linux.ibm.com>
Tested-by: Yu Zhao <yuzhao@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: SeongJae Park <sj@kernel.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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