[REGRESSION v5.2-rc] SUNRPC: Declare RPC timers as TIMER_DEFERRABLE (431235818bc3)

From: Jon Hunter
Date: Wed Jun 05 2019 - 04:45:09 EST


Hi Trond,

I have been noticing intermittent failures with a system suspend test on
some of our machines that have a NFS mounted root file-system. Bisecting
this issue points to your commit 431235818bc3 ("SUNRPC: Declare RPC
timers as TIMER_DEFERRABLE") and reverting this on top of v5.2-rc3 does
appear to resolve the problem.

The cause of the suspend failure appears to be a long delay observed
sometimes when resuming from suspend, and this is causing our test to
timeout. For example, in a failing case I see something like the
following ...

[ 69.667385] PM: suspend entry (deep)

[ 69.675642] Filesystems sync: 0.000 seconds

[ 69.684983] Freezing user space processes ... (elapsed 0.001 seconds) done.

[ 69.697880] OOM killer disabled.

[ 69.705670] Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done.

[ 69.719043] printk: Suspending console(s) (use no_console_suspend to debug)

[ 69.758911] Disabling non-boot CPUs ...

[ 69.761875] IRQ 17: no longer affine to CPU3

[ 69.762609] Entering suspend state LP1

[ 69.762636] Enabling non-boot CPUs ...

[ 69.763600] CPU1 is up

[ 69.764517] CPU2 is up

[ 69.765532] CPU3 is up

[ 69.845832] mmc1: queuing unknown CIS tuple 0x80 (50 bytes)

[ 69.854223] mmc1: queuing unknown CIS tuple 0x80 (7 bytes)

[ 69.857238] mmc1: queuing unknown CIS tuple 0x80 (7 bytes)

[ 69.892700] mmc1: queuing unknown CIS tuple 0x02 (1 bytes)

[ 70.407286] OOM killer enabled.

[ 70.414674] Restarting tasks ... done.

[ 70.423232] PM: suspend exit

[ 73.533252] asix 1-1:1.0 eth0: link up, 100Mbps, full-duplex, lpa 0xCDE1

[ 105.461852] nfs: server 192.168.99.1 not responding, still trying

[ 105.462347] nfs: server 192.168.99.1 not responding, still trying

[ 105.484809] nfs: server 192.168.99.1 OK

[ 105.486454] nfs: server 192.168.99.1 OK


So it would appear that making these timers deferrable is having an impact
when resuming from suspend. Do you have any thoughts on this?

Thanks
Jon