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Taehee Yoo bf0ce5aa5f xdp: fix invalid wait context of page_pool_destroy() 
[ Upstream commit 59a931c5b7 ]

If the driver uses a page pool, it creates a page pool with
page_pool_create().
The reference count of page pool is 1 as default.
A page pool will be destroyed only when a reference count reaches 0.
page_pool_destroy() is used to destroy page pool, it decreases a
reference count.
When a page pool is destroyed, ->disconnect() is called, which is
mem_allocator_disconnect().
This function internally acquires mutex_lock().

If the driver uses XDP, it registers a memory model with
xdp_rxq_info_reg_mem_model().
The xdp_rxq_info_reg_mem_model() internally increases a page pool
reference count if a memory model is a page pool.
Now the reference count is 2.

To destroy a page pool, the driver should call both page_pool_destroy()
and xdp_unreg_mem_model().
The xdp_unreg_mem_model() internally calls page_pool_destroy().
Only page_pool_destroy() decreases a reference count.

If a driver calls page_pool_destroy() then xdp_unreg_mem_model(), we
will face an invalid wait context warning.
Because xdp_unreg_mem_model() calls page_pool_destroy() with
rcu_read_lock().
The page_pool_destroy() internally acquires mutex_lock().

Splat looks like:
=============================
[ BUG: Invalid wait context ]
6.10.0-rc6+ #4 Tainted: G W
-----------------------------
ethtool/1806 is trying to lock:
ffffffff90387b90 (mem_id_lock){+.+.}-{4:4}, at: mem_allocator_disconnect+0x73/0x150
other info that might help us debug this:
context-{5:5}
3 locks held by ethtool/1806:
stack backtrace:
CPU: 0 PID: 1806 Comm: ethtool Tainted: G W 6.10.0-rc6+ #4 f916f41f172891c800f2fed
Hardware name: ASUS System Product Name/PRIME Z690-P D4, BIOS 0603 11/01/2021
Call Trace:
<TASK>
dump_stack_lvl+0x7e/0xc0
__lock_acquire+0x1681/0x4de0
? _printk+0x64/0xe0
? __pfx_mark_lock.part.0+0x10/0x10
? __pfx___lock_acquire+0x10/0x10
lock_acquire+0x1b3/0x580
? mem_allocator_disconnect+0x73/0x150
? __wake_up_klogd.part.0+0x16/0xc0
? __pfx_lock_acquire+0x10/0x10
? dump_stack_lvl+0x91/0xc0
__mutex_lock+0x15c/0x1690
? mem_allocator_disconnect+0x73/0x150
? __pfx_prb_read_valid+0x10/0x10
? mem_allocator_disconnect+0x73/0x150
? __pfx_llist_add_batch+0x10/0x10
? console_unlock+0x193/0x1b0
? lockdep_hardirqs_on+0xbe/0x140
? __pfx___mutex_lock+0x10/0x10
? tick_nohz_tick_stopped+0x16/0x90
? __irq_work_queue_local+0x1e5/0x330
? irq_work_queue+0x39/0x50
? __wake_up_klogd.part.0+0x79/0xc0
? mem_allocator_disconnect+0x73/0x150
mem_allocator_disconnect+0x73/0x150
? __pfx_mem_allocator_disconnect+0x10/0x10
? mark_held_locks+0xa5/0xf0
? rcu_is_watching+0x11/0xb0
page_pool_release+0x36e/0x6d0
page_pool_destroy+0xd7/0x440
xdp_unreg_mem_model+0x1a7/0x2a0
? __pfx_xdp_unreg_mem_model+0x10/0x10
? kfree+0x125/0x370
? bnxt_free_ring.isra.0+0x2eb/0x500
? bnxt_free_mem+0x5ac/0x2500
xdp_rxq_info_unreg+0x4a/0xd0
bnxt_free_mem+0x1356/0x2500
bnxt_close_nic+0xf0/0x3b0
? __pfx_bnxt_close_nic+0x10/0x10
? ethnl_parse_bit+0x2c6/0x6d0
? __pfx___nla_validate_parse+0x10/0x10
? __pfx_ethnl_parse_bit+0x10/0x10
bnxt_set_features+0x2a8/0x3e0
__netdev_update_features+0x4dc/0x1370
? ethnl_parse_bitset+0x4ff/0x750
? __pfx_ethnl_parse_bitset+0x10/0x10
? __pfx___netdev_update_features+0x10/0x10
? mark_held_locks+0xa5/0xf0
? _raw_spin_unlock_irqrestore+0x42/0x70
? __pm_runtime_resume+0x7d/0x110
ethnl_set_features+0x32d/0xa20

To fix this problem, it uses rhashtable_lookup_fast() instead of
rhashtable_lookup() with rcu_read_lock().
Using xa without rcu_read_lock() here is safe.
xa is freed by __xdp_mem_allocator_rcu_free() and this is called by
call_rcu() of mem_xa_remove().
The mem_xa_remove() is called by page_pool_destroy() if a reference
count reaches 0.
The xa is already protected by the reference count mechanism well in the
control plane.
So removing rcu_read_lock() for page_pool_destroy() is safe.

Fixes: c3f812cea0 ("page_pool: do not release pool until inflight == 0.")
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Link: https://patch.msgid.link/20240712095116.3801586-1-ap420073@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2024-08-03 08:53:44 +02:00
arch perf/x86/intel/cstate: Fix Alderlake/Raptorlake/Meteorlake 2024-08-03 08:53:41 +02:00
block block/mq-deadline: Fix the tag reservation code 2024-08-03 08:53:22 +02:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: aead,cipher - zeroize key buffer after use 2024-07-11 12:49:04 +02:00
Documentation scsi: sr: Fix unintentional arithmetic wraparound 2024-07-25 09:50:40 +02:00
drivers Bluetooth: btnxpuart: Add handling for boot-signature timeout errors 2024-08-03 08:53:44 +02:00
fs udf: Fix bogus checksum computation in udf_rename() 2024-08-03 08:53:39 +02:00
include bpf: Fix null pointer dereference in resolve_prog_type() for BPF_PROG_TYPE_EXT 2024-08-03 08:53:44 +02:00
init smp: Provide 'setup_max_cpus' definition on UP too 2024-06-16 13:47:49 +02:00
io_uring io_uring/rsrc: fix incorrect assignment of iter->nr_segs in io_import_fixed 2024-06-27 13:49:10 +02:00
ipc Add x86 shadow stack support 2023-08-31 12:20:12 -07:00
kernel bpf: Eliminate remaining "make W=1" warnings in kernel/bpf/btf.o 2024-08-03 08:53:43 +02:00
lib mlxsw: spectrum_acl_erp: Fix object nesting warning 2024-08-03 08:53:38 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: page_ref: remove folio_try_get_rcu() 2024-07-25 09:50:56 +02:00
net xdp: fix invalid wait context of page_pool_destroy() 2024-08-03 08:53:44 +02:00
rust rust: kernel: require Send for Module implementations 2024-05-17 12:01:56 +02:00
samples work around gcc bugs with 'asm goto' with outputs 2024-02-23 09:24:47 +01:00
scripts x86/kconfig: Add as-instr64 macro to properly evaluate AS_WRUSS 2024-08-03 08:53:21 +02:00
security ima: Avoid blocking in RCU read-side critical section 2024-07-11 12:49:18 +02:00
sound ALSA: seq: ump: Skip useless ports for static blocks 2024-07-27 11:34:10 +02:00
tools selftests: forwarding: devlink_lib: Wait for udev events after reloading 2024-08-03 08:53:44 +02:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt KVM: Fix a data race on last_boosted_vcpu in kvm_vcpu_on_spin() 2024-06-27 13:49:11 +02:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: rpm-pkg: rename binkernel.spec to kernel.spec 2023-07-25 00:59:33 +09:00
.mailmap 20 hotfixes. 12 are cc:stable and the remainder address post-6.5 issues 2023-10-24 09:52:16 -10:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS pwm: Rename pwm_apply_state() to pwm_apply_might_sleep() 2024-06-12 11:12:24 +02:00
Makefile Linux 6.6.43 2024-07-27 11:34:11 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.