Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

On Mon, Jan 04, 2016 at 11:07:43AM -0800, Andy Lutomirski wrote: > On Mon, Jan 4, 2016 at 8:09 AM, Dominique Martinet > wrote: > > Peter Zijlstra wrote on Mon, Jan 04, 2016 at 04:59:15PM +0100: > >> On Tue, Dec 29, 2015 at 10:43:26PM -0800, Andy Lutomirski wrote: > >> > [add cc's] > >> > > >> >

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

On Mon, Jan 4, 2016 at 8:09 AM, Dominique Martinet wrote: > Peter Zijlstra wrote on Mon, Jan 04, 2016 at 04:59:15PM +0100: >> On Tue, Dec 29, 2015 at 10:43:26PM -0800, Andy Lutomirski wrote: >> > [add cc's] >> > >> > Hi scheduler people: >> > >> > This is relatively easy for me to reproduce. Any

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

Peter Zijlstra wrote on Mon, Jan 04, 2016 at 04:59:15PM +0100: > On Tue, Dec 29, 2015 at 10:43:26PM -0800, Andy Lutomirski wrote: > > [add cc's] > > > > Hi scheduler people: > > > > This is relatively easy for me to reproduce. Any hints for debugging > > it? Could we really have a bug in which

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

On Tue, Dec 29, 2015 at 10:43:26PM -0800, Andy Lutomirski wrote: > [add cc's] > > Hi scheduler people: > > This is relatively easy for me to reproduce. Any hints for debugging > it? Could we really have a bug in which processes that are > schedulable as a result of mutex unlock aren't always

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

On Mon, Jan 04, 2016 at 11:07:43AM -0800, Andy Lutomirski wrote: > On Mon, Jan 4, 2016 at 8:09 AM, Dominique Martinet > wrote: > > Peter Zijlstra wrote on Mon, Jan 04, 2016 at 04:59:15PM +0100: > >> On Tue, Dec 29, 2015 at 10:43:26PM -0800, Andy Lutomirski wrote: > >> >

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

On Mon, Jan 4, 2016 at 8:09 AM, Dominique Martinet wrote: > Peter Zijlstra wrote on Mon, Jan 04, 2016 at 04:59:15PM +0100: >> On Tue, Dec 29, 2015 at 10:43:26PM -0800, Andy Lutomirski wrote: >> > [add cc's] >> > >> > Hi scheduler people: >> > >> > This is relatively

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

On Tue, Dec 29, 2015 at 10:43:26PM -0800, Andy Lutomirski wrote: > [add cc's] > > Hi scheduler people: > > This is relatively easy for me to reproduce. Any hints for debugging > it? Could we really have a bug in which processes that are > schedulable as a result of mutex unlock aren't always

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

Peter Zijlstra wrote on Mon, Jan 04, 2016 at 04:59:15PM +0100: > On Tue, Dec 29, 2015 at 10:43:26PM -0800, Andy Lutomirski wrote: > > [add cc's] > > > > Hi scheduler people: > > > > This is relatively easy for me to reproduce. Any hints for debugging > > it? Could we really have a bug in which

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

[add cc's] Hi scheduler people: This is relatively easy for me to reproduce. Any hints for debugging it? Could we really have a bug in which processes that are schedulable as a result of mutex unlock aren't always reliably scheduled? --Andy On Thu, Dec 24, 2015 at 2:51 AM, Dominique Martinet

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

[add cc's] Hi scheduler people: This is relatively easy for me to reproduce. Any hints for debugging it? Could we really have a bug in which processes that are schedulable as a result of mutex unlock aren't always reliably scheduled? --Andy On Thu, Dec 24, 2015 at 2:51 AM, Dominique Martinet

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

Andy Lutomirski wrote on Thu, Dec 17, 2015: > This could be QEMU's analysis script screwing up. Is there a good way > for me to gather more info? I finally took some time to reproduce it (sorry for the delay) Using your config, virtme commit (17363c2) and kernel tag v4.4-rc3 I was able to

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

Andy Lutomirski wrote on Thu, Dec 17, 2015: > This could be QEMU's analysis script screwing up. Is there a good way > for me to gather more info? I finally took some time to reproduce it (sorry for the delay) Using your config, virtme commit (17363c2) and kernel tag v4.4-rc3 I was able to

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

On Tue, Dec 8, 2015 at 10:45 PM, Al Viro wrote: > On Wed, Dec 09, 2015 at 07:23:16AM +0100, Dominique Martinet wrote: >> Andy Lutomirski wrote on Tue, Dec 08, 2015: >> > Trace attached. I don't see anything wrong, but I also don't know >> > what I'm looking for. >> >> Actually doesn't look good,

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

On Tue, Dec 8, 2015 at 10:45 PM, Al Viro wrote: > On Wed, Dec 09, 2015 at 07:23:16AM +0100, Dominique Martinet wrote: >> Andy Lutomirski wrote on Tue, Dec 08, 2015: >> > Trace attached. I don't see anything wrong, but I also don't know >> > what I'm looking for. >> >>

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

On Wed, Dec 09, 2015 at 07:23:16AM +0100, Dominique Martinet wrote: > Andy Lutomirski wrote on Tue, Dec 08, 2015: > > Trace attached. I don't see anything wrong, but I also don't know > > what I'm looking for. > > Actually doesn't look good, not sure if trace could be missing messages > but it

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

Dominique Martinet wrote on Wed, Dec 09, 2015: > Andy Lutomirski wrote on Tue, Dec 08, 2015: > > Trace attached. I don't see anything wrong, but I also don't know > > what I'm looking for. > > Actually doesn't look good, not sure if trace could be missing messages > but it looks like tags get

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

Andy Lutomirski wrote on Tue, Dec 08, 2015: > Trace attached. I don't see anything wrong, but I also don't know > what I'm looking for. Actually doesn't look good, not sure if trace could be missing messages but it looks like tags get reused... Quick and dirty parse script (attached output, it

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

On Mon, Dec 7, 2015 at 6:33 PM, Al Viro wrote: > On Mon, Dec 07, 2015 at 05:59:41PM -0800, Andy Lutomirski wrote: > >> If I dump all task states (see attached typescript), I see a bunch of >> things blocked in 9p rpc. This makes me think it could be a QEMU bug, >> not a kernel bug. > > Maybe,

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

On Mon, Dec 7, 2015 at 6:33 PM, Al Viro wrote: > On Mon, Dec 07, 2015 at 05:59:41PM -0800, Andy Lutomirski wrote: > >> If I dump all task states (see attached typescript), I see a bunch of >> things blocked in 9p rpc. This makes me think it could be a QEMU bug, >> not a

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

Dominique Martinet wrote on Wed, Dec 09, 2015: > Andy Lutomirski wrote on Tue, Dec 08, 2015: > > Trace attached. I don't see anything wrong, but I also don't know > > what I'm looking for. > > Actually doesn't look good, not sure if trace could be missing messages > but it looks like tags get

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

Andy Lutomirski wrote on Tue, Dec 08, 2015: > Trace attached. I don't see anything wrong, but I also don't know > what I'm looking for. Actually doesn't look good, not sure if trace could be missing messages but it looks like tags get reused... Quick and dirty parse script (attached output, it

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

On Wed, Dec 09, 2015 at 07:23:16AM +0100, Dominique Martinet wrote: > Andy Lutomirski wrote on Tue, Dec 08, 2015: > > Trace attached. I don't see anything wrong, but I also don't know > > what I'm looking for. > > Actually doesn't look good, not sure if trace could be missing messages > but it

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

On Mon, Dec 07, 2015 at 05:59:41PM -0800, Andy Lutomirski wrote: > If I dump all task states (see attached typescript), I see a bunch of > things blocked in 9p rpc. This makes me think it could be a QEMU bug, > not a kernel bug. Maybe, maybe not - I'd suggest dumping the 9p traffic and checking

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

On Mon, Dec 7, 2015 at 2:46 PM, Dominique Martinet wrote: > Andy Lutomirski wrote on Mon, Dec 07, 2015: >> On Thu, Dec 3, 2015 at 9:52 PM, Andy Lutomirski wrote: >> > Sometimes udevadm trigger --action=add hangs the system, and the splat >> > below happens. This seems to be timing dependent,

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

Andy Lutomirski wrote on Mon, Dec 07, 2015: > On Thu, Dec 3, 2015 at 9:52 PM, Andy Lutomirski wrote: > > Sometimes udevadm trigger --action=add hangs the system, and the splat > > below happens. This seems to be timing dependent, and I haven't been > > able to trigger it yet with lockdep

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

On Mon, Dec 07, 2015 at 05:59:41PM -0800, Andy Lutomirski wrote: > If I dump all task states (see attached typescript), I see a bunch of > things blocked in 9p rpc. This makes me think it could be a QEMU bug, > not a kernel bug. Maybe, maybe not - I'd suggest dumping the 9p traffic and checking

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

Andy Lutomirski wrote on Mon, Dec 07, 2015: > On Thu, Dec 3, 2015 at 9:52 PM, Andy Lutomirski wrote: > > Sometimes udevadm trigger --action=add hangs the system, and the splat > > below happens. This seems to be timing dependent, and I haven't been > > able to trigger it yet

Re: [V9fs-developer] Hang triggered by udev coldplug, looks like a race

On Mon, Dec 7, 2015 at 2:46 PM, Dominique Martinet wrote: > Andy Lutomirski wrote on Mon, Dec 07, 2015: >> On Thu, Dec 3, 2015 at 9:52 PM, Andy Lutomirski wrote: >> > Sometimes udevadm trigger --action=add hangs the system, and the splat >> > below