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018349d70f
When netvsc device is removed it can call reschedule in RCU context.
This happens because canceling the subchannel setup work could (in theory)
cause a reschedule when manipulating the timer.
To reproduce, run with lockdep enabled kernel and unbind
a network device from hv_netvsc (via sysfs).
[ 160.682011] WARNING: suspicious RCU usage
[ 160.707466] 4.19.0-rc3-uio+ #2 Not tainted
[ 160.709937] -----------------------------
[ 160.712352] ./include/linux/rcupdate.h:302 Illegal context switch in RCU read-side critical section!
[ 160.723691]
[ 160.723691] other info that might help us debug this:
[ 160.723691]
[ 160.730955]
[ 160.730955] rcu_scheduler_active = 2, debug_locks = 1
[ 160.762813] 5 locks held by rebind-eth.sh/1812:
[ 160.766851] #0: 000000008befa37a (sb_writers#6){.+.+}, at: vfs_write+0x184/0x1b0
[ 160.773416] #1: 00000000b097f236 (&of->mutex){+.+.}, at: kernfs_fop_write+0xe2/0x1a0
[ 160.783766] #2: 0000000041ee6889 (kn->count#3){++++}, at: kernfs_fop_write+0xeb/0x1a0
[ 160.787465] #3: 0000000056d92a74 (&dev->mutex){....}, at: device_release_driver_internal+0x39/0x250
[ 160.816987] #4: 0000000030f6031e (rcu_read_lock){....}, at: netvsc_remove+0x1e/0x250 [hv_netvsc]
[ 160.828629]
[ 160.828629] stack backtrace:
[ 160.831966] CPU: 1 PID: 1812 Comm: rebind-eth.sh Not tainted 4.19.0-rc3-uio+ #2
[ 160.832952] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine, BIOS Hyper-V UEFI Release v1.0 11/26/2012
[ 160.832952] Call Trace:
[ 160.832952] dump_stack+0x85/0xcb
[ 160.832952] ___might_sleep+0x1a3/0x240
[ 160.832952] __flush_work+0x57/0x2e0
[ 160.832952] ? __mutex_lock+0x83/0x990
[ 160.832952] ? __kernfs_remove+0x24f/0x2e0
[ 160.832952] ? __kernfs_remove+0x1b2/0x2e0
[ 160.832952] ? mark_held_locks+0x50/0x80
[ 160.832952] ? get_work_pool+0x90/0x90
[ 160.832952] __cancel_work_timer+0x13c/0x1e0
[ 160.832952] ? netvsc_remove+0x1e/0x250 [hv_netvsc]
[ 160.832952] ? __lock_is_held+0x55/0x90
[ 160.832952] netvsc_remove+0x9a/0x250 [hv_netvsc]
[ 160.832952] vmbus_remove+0x26/0x30
[ 160.832952] device_release_driver_internal+0x18a/0x250
[ 160.832952] unbind_store+0xb4/0x180
[ 160.832952] kernfs_fop_write+0x113/0x1a0
[ 160.832952] __vfs_write+0x36/0x1a0
[ 160.832952] ? rcu_read_lock_sched_held+0x6b/0x80
[ 160.832952] ? rcu_sync_lockdep_assert+0x2e/0x60
[ 160.832952] ? __sb_start_write+0x141/0x1a0
[ 160.832952] ? vfs_write+0x184/0x1b0
[ 160.832952] vfs_write+0xbe/0x1b0
[ 160.832952] ksys_write+0x55/0xc0
[ 160.832952] do_syscall_64+0x60/0x1b0
[ 160.832952] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 160.832952] RIP: 0033:0x7fe48f4c8154
Resolve this by getting RTNL earlier. This is safe because the subchannel
work queue does trylock on RTNL and will detect the race.
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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.
See Documentation/00-INDEX for a list of what is contained in each file.
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.