On Thu, 8 Jun 2023 21:20:04 -0300 "Luis Claudio R. Goncalves" <lgoncalv@xxxxxxxxxx> wrote: > Sebastian, Steven, > > I don't know if this is the best solution for the problem, but surely the > simplest one. If this patch makes sense, it could probably go upstream as > the changes only affect RT. > > ------- > > rt: vmd: make cfg_lock a raw spinlock > > This call sequence triggers the backtrace listed below: > > pci_user_read_config_dword() ---> vmd_pci_read() Since pci_user_read_config_dword() (and all other sizes) uses raw_spin_lock(), I guess there's really no other choice than to have vmd_pci_read() do the same. -- Steve > > The first function, pci_user_read_config_dword(), takes a raw_spin_lock > (a classic spin lock) and disables preemption and interrupts. Then > vmd_pci_read() takes a RT spinlock (a rtmutex), which can sleep, hence > the complaint about a sleeping function being called from atomic context. > > > [ 168.466387] LTP: starting read_all_proc (read_all -d /proc -q -r 3) > [ 168.614389] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48 > [ 168.614393] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 10268, name: read_all > [ 168.614395] preempt_count: 1, expected: 0 > [ 168.614396] RCU nest depth: 0, expected: 0 > [ 168.614397] INFO: lockdep is turned off. > [ 168.614398] irq event stamp: 0 > [ 168.614398] hardirqs last enabled at (0): [<0000000000000000>] 0x0 > [ 168.614402] hardirqs last disabled at (0): [<ffffffffa4b0f3bf>] copy_process+0x80f/0x1990 > [ 168.614411] softirqs last enabled at (0): [<ffffffffa4b0f3bf>] copy_process+0x80f/0x1990 > [ 168.614414] softirqs last disabled at (0): [<0000000000000000>] 0x0 > [ 168.614415] Preemption disabled at: > [ 168.614416] [<0000000000000000>] 0x0 > [ 168.614418] CPU: 19 PID: 10268 Comm: read_all Tainted: G W 6.4.0-rc5-rt4 #2 > [ 168.614421] Hardware name: Dell Inc. Precision 7820 Tower/0804P1, BIOS 2.6.3 05/04/2020 > [ 168.614422] Call Trace: > [ 168.614424] <TASK> > [ 168.614425] dump_stack_lvl+0x47/0x80 > [ 168.614433] __might_resched+0x19b/0x250 > [ 168.614441] rt_spin_lock+0x4c/0x100 > [ 168.614446] ? vmd_pci_read+0x85/0xf0 > [ 168.614453] vmd_pci_read+0x85/0xf0 > [ 168.614456] pci_user_read_config_dword+0x78/0x100
