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On 05/31, Jason Wang wrote: > > On Wed, May 31, 2023 at 3:25?PM Oleg Nesterov <oleg at redhat.com> wrote: > > > > On 05/31, Jason Wang wrote: > > > > > > ? 2023/5/23 20:15, Oleg Nesterov ??: > > > > > > > > /* make sure flag is seen after deletion */ > > > > smp_wmb(); > > &...

On 06/06, Mike Christie wrote: > > On 6/6/23 7:16 AM, Oleg Nesterov wrote: > > On 06/05, Mike Christie wrote: > > > >> So it works like if we were using a kthread still: > >> > >> 1. Userapce thread0 opens /dev/vhost-$something. > >> 2. thread0 does VHOST_SET_OWNER ioctl. This calls vhost_task_create() to > >&gt...

On 02/11, Raghavendra K T wrote: > > On 02/10/2015 06:56 PM, Oleg Nesterov wrote: > >> In this case __ticket_check_and_clear_slowpath() really needs to cmpxchg >> the whole .head_tail. Plus obviously more boring changes. This needs a >> separate patch even _if_ this can work. > > Correct, but apart from this, before doing xadd in unlock, > we...

On 02/11, Raghavendra K T wrote: > > On 02/10/2015 06:56 PM, Oleg Nesterov wrote: > >> In this case __ticket_check_and_clear_slowpath() really needs to cmpxchg >> the whole .head_tail. Plus obviously more boring changes. This needs a >> separate patch even _if_ this can work. > > Correct, but apart from this, before doing xadd in unlock, > we...

On 05/22, Oleg Nesterov wrote: > > Right now I think that "int dead" should die, No, probably we shouldn't call get_signal() if we have already dequeued SIGKILL. > but let me think tomorrow. May be something like this... I don't like it but I can't suggest anything better right now. boo...

On Wed, May 31, 2023 at 5:14?PM Oleg Nesterov <oleg at redhat.com> wrote: > > On 05/31, Jason Wang wrote: > > > > On Wed, May 31, 2023 at 3:25?PM Oleg Nesterov <oleg at redhat.com> wrote: > > > > > > On 05/31, Jason Wang wrote: > > > > > > > > ? 2023/5/23 20:15, Oleg Neste...

On 06/05, Mike Christie wrote: > > On 6/5/23 10:10 AM, Oleg Nesterov wrote: > > On 06/03, michael.christie at oracle.com wrote: > >> > >> On 6/2/23 11:15 PM, Eric W. Biederman wrote: > >> The problem is that as part of the flush the drivers/vhost/scsi.c code > >> will wait for outstanding commands, because we can't free...

On 6/6/23 7:16 AM, Oleg Nesterov wrote: > On 06/05, Mike Christie wrote: >> >> On 6/5/23 10:10 AM, Oleg Nesterov wrote: >>> On 06/03, michael.christie at oracle.com wrote: >>>> >>>> On 6/2/23 11:15 PM, Eric W. Biederman wrote: >>>> The problem is that as part of the flush...

On 02/10, Raghavendra K T wrote: > > On 02/10/2015 06:23 AM, Linus Torvalds wrote: > >> add_smp(&lock->tickets.head, TICKET_LOCK_INC); >> if (READ_ONCE(lock->tickets.tail) & TICKET_SLOWPATH_FLAG) .. >> >> into something like >> >> val = xadd((&lock->ticket.head_tail, TICKET_LOCK_INC << TICKET_SHIFT);

On 02/10, Raghavendra K T wrote: > > On 02/10/2015 06:23 AM, Linus Torvalds wrote: > >> add_smp(&lock->tickets.head, TICKET_LOCK_INC); >> if (READ_ONCE(lock->tickets.tail) & TICKET_SLOWPATH_FLAG) .. >> >> into something like >> >> val = xadd((&lock->ticket.head_tail, TICKET_LOCK_INC << TICKET_SHIFT);

On 02/10, Jeremy Fitzhardinge wrote: > > On 02/10/2015 05:26 AM, Oleg Nesterov wrote: > > On 02/10, Raghavendra K T wrote: > >> Unfortunately xadd could result in head overflow as tail is high. > >> > >> The other option was repeated cmpxchg which is bad I believe. > >> Any suggestions? > > Stupid question... what if we simply m...

On 02/10, Jeremy Fitzhardinge wrote: > > On 02/10/2015 05:26 AM, Oleg Nesterov wrote: > > On 02/10, Raghavendra K T wrote: > >> Unfortunately xadd could result in head overflow as tail is high. > >> > >> The other option was repeated cmpxchg which is bad I believe. > >> Any suggestions? > > Stupid question... what if we simply m...

On 02/13/2015 09:02 PM, Oleg Nesterov wrote: > On 02/13, Raghavendra K T wrote: >> >> @@ -164,7 +161,7 @@ static inline int arch_spin_is_locked(arch_spinlock_t *lock) >> { >> struct __raw_tickets tmp = READ_ONCE(lock->tickets); >> >> - return tmp.tail != tmp.head; >> + return tmp.tai...

On 02/13/2015 09:02 PM, Oleg Nesterov wrote: > On 02/13, Raghavendra K T wrote: >> >> @@ -164,7 +161,7 @@ static inline int arch_spin_is_locked(arch_spinlock_t *lock) >> { >> struct __raw_tickets tmp = READ_ONCE(lock->tickets); >> >> - return tmp.tail != tmp.head; >> + return tmp.tai...

...terZ: Detailed changelog] > > > > Reported-by: Sasha Levin <sasha.levin at oracle.com> > > Suggested-by: Linus Torvalds <torvalds at linux-foundation.org> > > Signed-off-by: Raghavendra K T <raghavendra.kt at linux.vnet.ibm.com> > > Reviewed-by: Oleg Nesterov <oleg at redhat.com> > > Acked-by: David Vrabel <david.vrabel at citrix.com> > > --- > > arch/x86/include/asm/spinlock.h | 94 ++++++++++++++++++++--------------------- > > arch/x86/kernel/kvm.c | 7 ++- > > arch/x86/xen/spinlock.c | 7...

...terZ: Detailed changelog] > > > > Reported-by: Sasha Levin <sasha.levin at oracle.com> > > Suggested-by: Linus Torvalds <torvalds at linux-foundation.org> > > Signed-off-by: Raghavendra K T <raghavendra.kt at linux.vnet.ibm.com> > > Reviewed-by: Oleg Nesterov <oleg at redhat.com> > > Acked-by: David Vrabel <david.vrabel at citrix.com> > > --- > > arch/x86/include/asm/spinlock.h | 94 ++++++++++++++++++++--------------------- > > arch/x86/kernel/kvm.c | 7 ++- > > arch/x86/xen/spinlock.c | 7...

On 6/5/23 10:10 AM, Oleg Nesterov wrote: > On 06/03, michael.christie at oracle.com wrote: >> >> On 6/2/23 11:15 PM, Eric W. Biederman wrote: >> The problem is that as part of the flush the drivers/vhost/scsi.c code >> will wait for outstanding commands, because we can't free the device and >> i...

On 05/22, Mike Christie wrote: > > On 5/22/23 7:30 AM, Oleg Nesterov wrote: > >> + /* > >> + * When we get a SIGKILL our release function will > >> + * be called. That will stop new IOs from being queued > >> + * and check for outstanding cmd responses. It will then > >> + * call vhost_task_stop to tell us t...

Oleg Nesterov <oleg at redhat.com> writes: > On 05/22, Oleg Nesterov wrote: >> >> Right now I think that "int dead" should die, > > No, probably we shouldn't call get_signal() if we have already > dequeued SIGKILL. Very much agreed. It is one thing to add a patch to...

...ing slowpath flag to head, ticket_equals idea] [PeterZ: Detailed changelog] Reported-by: Sasha Levin <sasha.levin at oracle.com> Suggested-by: Linus Torvalds <torvalds at linux-foundation.org> Signed-off-by: Raghavendra K T <raghavendra.kt at linux.vnet.ibm.com> Reviewed-by: Oleg Nesterov <oleg at redhat.com> Acked-by: David Vrabel <david.vrabel at citrix.com> --- arch/x86/include/asm/spinlock.h | 94 ++++++++++++++++++++--------------------- arch/x86/kernel/kvm.c | 7 ++- arch/x86/xen/spinlock.c | 7 ++- 3 files changed, 58 insertions(+), 50 deletio...