commit d9ec73301099ec5975505e1c3effbe768bab9490 upstream.
After commit 0a65bc27bd64 ("eventpoll: Set epoll timeout if it's in
the future"), the following program would immediately enter a busy
loop in the kernel:
```
int main() {
int e = epoll_create1(0);
struct epoll_event event = {.events = EPOLLIN};
epoll_ctl(e, EPOLL_CTL_ADD, 0, &event);
const struct timespec timeout = {.tv_nsec = 1};
epoll_pwait2(e, &event, 1, &timeout, 0);
}
```
This happens because the given (non-zero) timeout of 1 nanosecond
usually expires before ep_poll() is entered and then
ep_schedule_timeout() returns false, but `timed_out` is never set
because the code line that sets it is skipped. This quickly turns
into a soft lockup, RCU stalls and deadlocks, inflicting severe
headaches to the whole system.
When the timeout has expired, we don't need to schedule a hrtimer, but
we should set the `timed_out` variable. Therefore, I suggest moving
the ep_schedule_timeout() check into the `timed_out` expression
instead of skipping it.
brauner: Note that there was an earlier fix by Joe Damato in response to
my bug report in [1].
Fixes: 0a65bc27bd64 ("eventpoll: Set epoll timeout if it's in the future")
Cc: Joe Damato <jdamato@fastly.com>
Cc: stable@vger.kernel.org
Signed-off-by: Max Kellermann <max.kellermann@ionos.com>
Link: https://lore.kernel.org/20250429153419.94723-1-jdamato@fastly.com [1]
Link: https://lore.kernel.org/20250429185827.3564438-1-max.kellermann@ionos.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 0a65bc27bd645894175c059397b4916e31955fb2 ]
Avoid an edge case where epoll_wait arms a timer and calls schedule()
even if the timer will expire immediately.
For example: if the user has specified an epoll busy poll usecs which is
equal or larger than the epoll_wait/epoll_pwait2 timeout, it is
unnecessary to call schedule_hrtimeout_range; the busy poll usecs have
consumed the entire timeout duration so it is unnecessary to induce
scheduling latency by calling schedule() (via schedule_hrtimeout_range).
This can be measured using a simple bpftrace script:
tracepoint:sched:sched_switch
/ args->prev_pid == $1 /
{
print(kstack());
print(ustack());
}
Before this patch is applied:
Testing an epoll_wait app with busy poll usecs set to 1000, and
epoll_wait timeout set to 1ms using the script above shows:
__traceiter_sched_switch+69
__schedule+1495
schedule+32
schedule_hrtimeout_range+159
do_epoll_wait+1424
__x64_sys_epoll_wait+97
do_syscall_64+95
entry_SYSCALL_64_after_hwframe+118
epoll_wait+82
Which is unexpected; the busy poll usecs should have consumed the
entire timeout and there should be no reason to arm a timer.
After this patch is applied: the same test scenario does not generate a
call to schedule() in the above edge case. If the busy poll usecs are
reduced (for example usecs: 100, epoll_wait timeout 1ms) the timer is
armed as expected.
Fixes: bf3b9f6372c4 ("epoll: Add busy poll support to epoll with socket fds.")
Signed-off-by: Joe Damato <jdamato@fastly.com>
Link: https://lore.kernel.org/20250416185826.26375-1-jdamato@fastly.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 38d203560118a673018df5892a6555bb0aba7762 ]
In preparation for reusing this helper in another epoll setup helper,
abstract it out.
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Link: https://lore.kernel.org/r/20250219172552.1565603-3-axboe@kernel.dk
Signed-off-by: Christian Brauner <brauner@kernel.org>
Stable-dep-of: 0a65bc27bd64 ("eventpoll: Set epoll timeout if it's in the future")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Add the const qualifier to all the ctl_tables in the tree except for
watchdog_hardlockup_sysctl, memory_allocation_profiling_sysctls,
loadpin_sysctl_table and the ones calling register_net_sysctl (./net,
drivers/inifiniband dirs). These are special cases as they use a
registration function with a non-const qualified ctl_table argument or
modify the arrays before passing them on to the registration function.
Constifying ctl_table structs will prevent the modification of
proc_handler function pointers as the arrays would reside in .rodata.
This is made possible after commit 78eb4ea25cd5 ("sysctl: treewide:
constify the ctl_table argument of proc_handlers") constified all the
proc_handlers.
Created this by running an spatch followed by a sed command:
Spatch:
virtual patch
@
depends on !(file in "net")
disable optional_qualifier
@
identifier table_name != {
watchdog_hardlockup_sysctl,
iwcm_ctl_table,
ucma_ctl_table,
memory_allocation_profiling_sysctls,
loadpin_sysctl_table
};
@@
+ const
struct ctl_table table_name [] = { ... };
sed:
sed --in-place \
-e "s/struct ctl_table .table = &uts_kern/const struct ctl_table *table = \&uts_kern/" \
kernel/utsname_sysctl.c
Reviewed-by: Song Liu <song@kernel.org>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org> # for kernel/trace/
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com> # SCSI
Reviewed-by: Darrick J. Wong <djwong@kernel.org> # xfs
Acked-by: Jani Nikula <jani.nikula@intel.com>
Acked-by: Corey Minyard <cminyard@mvista.com>
Acked-by: Wei Liu <wei.liu@kernel.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Bill O'Donnell <bodonnel@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
Acked-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Acked-by: Anna Schumaker <anna.schumaker@oracle.com>
Signed-off-by: Joel Granados <joel.granados@kernel.org>
Pull networking updates from Paolo Abeni:
"The most significant set of changes is the per netns RTNL. The new
behavior is disabled by default, regression risk should be contained.
Notably the new config knob PTP_1588_CLOCK_VMCLOCK will inherit its
default value from PTP_1588_CLOCK_KVM, as the first is intended to be
a more reliable replacement for the latter.
Core:
- Started a very large, in-progress, effort to make the RTNL lock
scope per network-namespace, thus reducing the lock contention
significantly in the containerized use-case, comprising:
- RCU-ified some relevant slices of the FIB control path
- introduce basic per netns locking helpers
- namespacified the IPv4 address hash table
- remove rtnl_register{,_module}() in favour of
rtnl_register_many()
- refactor rtnl_{new,del,set}link() moving as much validation as
possible out of RTNL lock
- convert all phonet doit() and dumpit() handlers to RCU
- convert IPv4 addresses manipulation to per-netns RTNL
- convert virtual interface creation to per-netns RTNL
the per-netns lock infrastructure is guarded by the
CONFIG_DEBUG_NET_SMALL_RTNL knob, disabled by default ad interim.
- Introduce NAPI suspension, to efficiently switching between busy
polling (NAPI processing suspended) and normal processing.
- Migrate the IPv4 routing input, output and control path from direct
ToS usage to DSCP macros. This is a work in progress to make ECN
handling consistent and reliable.
- Add drop reasons support to the IPv4 rotue input path, allowing
better introspection in case of packets drop.
- Make FIB seqnum lockless, dropping RTNL protection for read access.
- Make inet{,v6} addresses hashing less predicable.
- Allow providing timestamp OPT_ID via cmsg, to correlate TX packets
and timestamps
Things we sprinkled into general kernel code:
- Add small file operations for debugfs, to reduce the struct ops
size.
- Refactoring and optimization for the implementation of page_frag
API, This is a preparatory work to consolidate the page_frag
implementation.
Netfilter:
- Optimize set element transactions to reduce memory consumption
- Extended netlink error reporting for attribute parser failure.
- Make legacy xtables configs user selectable, giving users the
option to configure iptables without enabling any other config.
- Address a lot of false-positive RCU issues, pointed by recent CI
improvements.
BPF:
- Put xsk sockets on a struct diet and add various cleanups. Overall,
this helps to bump performance by 12% for some workloads.
- Extend BPF selftests to increase coverage of XDP features in
combination with BPF cpumap.
- Optimize and homogenize bpf_csum_diff helper for all archs and also
add a batch of new BPF selftests for it.
- Extend netkit with an option to delegate skb->{mark,priority}
scrubbing to its BPF program.
- Make the bpf_get_netns_cookie() helper available also to tc(x) BPF
programs.
Protocols:
- Introduces 4-tuple hash for connected udp sockets, speeding-up
significantly connected sockets lookup.
- Add a fastpath for some TCP timers that usually expires after
close, the socket lock contention.
- Add inbound and outbound xfrm state caches to speed up state
lookups.
- Avoid sending MPTCP advertisements on stale subflows, reducing
risks on loosing them.
- Make neighbours table flushing more scalable, maintaining per
device neigh lists.
Driver API:
- Introduce a unified interface to configure transmission H/W
shaping, and expose it to user-space via generic-netlink.
- Add support for per-NAPI config via netlink. This makes napi
configuration persistent across queues removal and re-creation.
Requires driver updates, currently supported drivers are:
nVidia/Mellanox mlx4 and mlx5, Broadcom brcm and Intel ice.
- Add ethtool support for writing SFP / PHY firmware blocks.
- Track RSS context allocation from ethtool core.
- Implement support for mirroring to DSA CPU port, via TC mirror
offload.
- Consolidate FDB updates notification, to avoid duplicates on
device-specific entries.
- Expose DPLL clock quality level to the user-space.
- Support master-slave PHY config via device tree.
Tests and tooling:
- forwarding: introduce deferred commands, to simplify the cleanup
phase
Drivers:
- Updated several drivers - Amazon vNic, Google vNic, Microsoft vNic,
Intel e1000e and Broadcom Tigon3 - to use netdev-genl to link the
IRQs and queues to NAPI IDs, allowing busy polling and better
introspection.
- Ethernet high-speed NICs:
- nVidia/Mellanox:
- mlx5:
- a large refactor to implement support for cross E-Switch
scheduling
- refactor H/W conter management to let it scale better
- H/W GRO cleanups
- Intel (100G, ice)::
- add support for ethtool reset
- implement support for per TX queue H/W shaping
- AMD/Solarflare:
- implement per device queue stats support
- Broadcom (bnxt):
- improve wildcard l4proto on IPv4/IPv6 ntuple rules
- Marvell Octeon:
- Add representor support for each Resource Virtualization Unit
(RVU) device.
- Hisilicon:
- add support for the BMC Gigabit Ethernet
- IBM (EMAC):
- driver cleanup and modernization
- Cisco (VIC):
- raise the queues number limit to 256
- Ethernet virtual:
- Google vNIC:
- implement page pool support
- macsec:
- inherit lower device's features and TSO limits when
offloading
- virtio_net:
- enable premapped mode by default
- support for XDP socket(AF_XDP) zerocopy TX
- wireguard:
- set the TSO max size to be GSO_MAX_SIZE, to aggregate larger
packets.
- Ethernet NICs embedded and virtual:
- Broadcom ASP:
- enable software timestamping
- Freescale:
- add enetc4 PF driver
- MediaTek: Airoha SoC:
- implement BQL support
- RealTek r8169:
- enable TSO by default on r8168/r8125
- implement extended ethtool stats
- Renesas AVB:
- enable TX checksum offload
- Synopsys (stmmac):
- support header splitting for vlan tagged packets
- move common code for DWMAC4 and DWXGMAC into a separate FPE
module.
- add dwmac driver support for T-HEAD TH1520 SoC
- Synopsys (xpcs):
- driver refactor and cleanup
- TI:
- icssg_prueth: add VLAN offload support
- Xilinx emaclite:
- add clock support
- Ethernet switches:
- Microchip:
- implement support for the lan969x Ethernet switch family
- add LAN9646 switch support to KSZ DSA driver
- Ethernet PHYs:
- Marvel: 88q2x: enable auto negotiation
- Microchip: add support for LAN865X Rev B1 and LAN867X Rev C1/C2
- PTP:
- Add support for the Amazon virtual clock device
- Add PtP driver for s390 clocks
- WiFi:
- mac80211
- EHT 1024 aggregation size for transmissions
- new operation to indicate that a new interface is to be added
- support radio separation of multi-band devices
- move wireless extension spy implementation to libiw
- Broadcom:
- brcmfmac: optional LPO clock support
- Microchip:
- add support for Atmel WILC3000
- Qualcomm (ath12k):
- firmware coredump collection support
- add debugfs support for a multitude of statistics
- Qualcomm (ath5k):
- Arcadyan ARV45XX AR2417 & Gigaset SX76[23] AR241[34]A support
- Realtek:
- rtw88: 8821au and 8812au USB adapters support
- rtw89: add thermal protection
- rtw89: fine tune BT-coexsitence to improve user experience
- rtw89: firmware secure boot for WiFi 6 chip
- Bluetooth
- add Qualcomm WCN785x support for ids Foxconn 0xe0fc/0xe0f3 and
0x13d3:0x3623
- add Realtek RTL8852BE support for id Foxconn 0xe123
- add MediaTek MT7920 support for wireless module ids
- btintel_pcie: add handshake between driver and firmware
- btintel_pcie: add recovery mechanism
- btnxpuart: add GPIO support to power save feature"
* tag 'net-next-6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1475 commits)
mm: page_frag: fix a compile error when kernel is not compiled
Documentation: tipc: fix formatting issue in tipc.rst
selftests: nic_performance: Add selftest for performance of NIC driver
selftests: nic_link_layer: Add selftest case for speed and duplex states
selftests: nic_link_layer: Add link layer selftest for NIC driver
bnxt_en: Add FW trace coredump segments to the coredump
bnxt_en: Add a new ethtool -W dump flag
bnxt_en: Add 2 parameters to bnxt_fill_coredump_seg_hdr()
bnxt_en: Add functions to copy host context memory
bnxt_en: Do not free FW log context memory
bnxt_en: Manage the FW trace context memory
bnxt_en: Allocate backing store memory for FW trace logs
bnxt_en: Add a 'force' parameter to bnxt_free_ctx_mem()
bnxt_en: Refactor bnxt_free_ctx_mem()
bnxt_en: Add mem_valid bit to struct bnxt_ctx_mem_type
bnxt_en: Update firmware interface spec to 1.10.3.85
selftests/bpf: Add some tests with sockmap SK_PASS
bpf: fix recursive lock when verdict program return SK_PASS
wireguard: device: support big tcp GSO
wireguard: selftests: load nf_conntrack if not present
...
Pull 'struct fd' class updates from Al Viro:
"The bulk of struct fd memory safety stuff
Making sure that struct fd instances are destroyed in the same scope
where they'd been created, getting rid of reassignments and passing
them by reference, converting to CLASS(fd{,_pos,_raw}).
We are getting very close to having the memory safety of that stuff
trivial to verify"
* tag 'pull-fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (28 commits)
deal with the last remaing boolean uses of fd_file()
css_set_fork(): switch to CLASS(fd_raw, ...)
memcg_write_event_control(): switch to CLASS(fd)
assorted variants of irqfd setup: convert to CLASS(fd)
do_pollfd(): convert to CLASS(fd)
convert do_select()
convert vfs_dedupe_file_range().
convert cifs_ioctl_copychunk()
convert media_request_get_by_fd()
convert spu_run(2)
switch spufs_calls_{get,put}() to CLASS() use
convert cachestat(2)
convert do_preadv()/do_pwritev()
fdget(), more trivial conversions
fdget(), trivial conversions
privcmd_ioeventfd_assign(): don't open-code eventfd_ctx_fdget()
o2hb_region_dev_store(): avoid goto around fdget()/fdput()
introduce "fd_pos" class, convert fdget_pos() users to it.
fdget_raw() users: switch to CLASS(fd_raw)
convert vmsplice() to CLASS(fd)
...
Pull vfs file updates from Christian Brauner:
"This contains changes the changes for files for this cycle:
- Introduce a new reference counting mechanism for files.
As atomic_inc_not_zero() is implemented with a try_cmpxchg() loop
it has O(N^2) behaviour under contention with N concurrent
operations and it is in a hot path in __fget_files_rcu().
The rcuref infrastructures remedies this problem by using an
unconditional increment relying on safe- and dead zones to make
this work and requiring rcu protection for the data structure in
question. This not just scales better it also introduces overflow
protection.
However, in contrast to generic rcuref, files require a memory
barrier and thus cannot rely on *_relaxed() atomic operations and
also require to be built on atomic_long_t as having massive amounts
of reference isn't unheard of even if it is just an attack.
This adds a file specific variant instead of making this a generic
library.
This has been tested by various people and it gives consistent
improvement up to 3-5% on workloads with loads of threads.
- Add a fastpath for find_next_zero_bit(). Skip 2-levels searching
via find_next_zero_bit() when there is a free slot in the word that
contains the next fd. This improves pts/blogbench-1.1.0 read by 8%
and write by 4% on Intel ICX 160.
- Conditionally clear full_fds_bits since it's very likely that a bit
in full_fds_bits has been cleared during __clear_open_fds(). This
improves pts/blogbench-1.1.0 read up to 13%, and write up to 5% on
Intel ICX 160.
- Get rid of all lookup_*_fdget_rcu() variants. They were used to
lookup files without taking a reference count. That became invalid
once files were switched to SLAB_TYPESAFE_BY_RCU and now we're
always taking a reference count. Switch to an already existing
helper and remove the legacy variants.
- Remove pointless includes of <linux/fdtable.h>.
- Avoid cmpxchg() in close_files() as nobody else has a reference to
the files_struct at that point.
- Move close_range() into fs/file.c and fold __close_range() into it.
- Cleanup calling conventions of alloc_fdtable() and expand_files().
- Merge __{set,clear}_close_on_exec() into one.
- Make __set_open_fd() set cloexec as well instead of doing it in two
separate steps"
* tag 'vfs-6.13.file' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
selftests: add file SLAB_TYPESAFE_BY_RCU recycling stressor
fs: port files to file_ref
fs: add file_ref
expand_files(): simplify calling conventions
make __set_open_fd() set cloexec state as well
fs: protect backing files with rcu
file.c: merge __{set,clear}_close_on_exec()
alloc_fdtable(): change calling conventions.
fs/file.c: add fast path in find_next_fd()
fs/file.c: conditionally clear full_fds
fs/file.c: remove sanity_check and add likely/unlikely in alloc_fd()
move close_range(2) into fs/file.c, fold __close_range() into it
close_files(): don't bother with xchg()
remove pointless includes of <linux/fdtable.h>
get rid of ...lookup...fdget_rcu() family
When events are reported to userland and prefer_busy_poll is set, irqs are temporarily suspended using napi_suspend_irqs. If no events are found and ep_poll would go to sleep, irq suspension is cancelled using napi_resume_irqs. Signed-off-by: Martin Karsten <mkarsten@uwaterloo.ca> Co-developed-by: Joe Damato <jdamato@fastly.com> Signed-off-by: Joe Damato <jdamato@fastly.com> Tested-by: Joe Damato <jdamato@fastly.com> Tested-by: Martin Karsten <mkarsten@uwaterloo.ca> Acked-by: Stanislav Fomichev <sdf@fomichev.me> Reviewed-by: Sridhar Samudrala <sridhar.samudrala@intel.com> Link: https://patch.msgid.link/20241109050245.191288-5-jdamato@fastly.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Setting prefer_busy_poll now leads to an effectively nonblocking iteration though napi_busy_loop, even when busy_poll_usecs is 0. Signed-off-by: Martin Karsten <mkarsten@uwaterloo.ca> Co-developed-by: Joe Damato <jdamato@fastly.com> Signed-off-by: Joe Damato <jdamato@fastly.com> Tested-by: Joe Damato <jdamato@fastly.com> Tested-by: Martin Karsten <mkarsten@uwaterloo.ca> Acked-by: Stanislav Fomichev <sdf@fomichev.me> Reviewed-by: Sridhar Samudrala <sridhar.samudrala@intel.com> Link: https://patch.msgid.link/20241109050245.191288-4-jdamato@fastly.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
all failure exits prior to fdget() leave the scope, all matching fdput() are immediately followed by leaving the scope. [xfs_ioc_commit_range() chunk moved here as well] Reviewed-by: Christian Brauner <brauner@kernel.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>