* Re: KVM patches applied in weird order in -stable [not found] <20160913145100.GK3872@codeblueprint.co.uk> @ 2016-09-13 14:58 ` Greg KH 2016-09-13 16:26 ` Paolo Bonzini 0 siblings, 1 reply; 5+ messages in thread From: Greg KH @ 2016-09-13 14:58 UTC (permalink / raw) To: Matt Fleming; +Cc: Paolo Bonzini, linux-kernel, stable [adding stable@ as this is a stable issue, not a 'normal' issue] On Tue, Sep 13, 2016 at 03:51:00PM +0100, Matt Fleming wrote: > Folks, > > While hunting down a performance issue involving KVM I was surprised > to see "native_set_debugreg()" as the first entry in `perf top`. > > Digging deeper, it looks as though the following patches were applied > in the wrong order in -stable. This is the order as they appear in > Linus' tree, > > [0] commit 4e422bdd2f84 ("KVM: x86: fix missed hardware breakpoints") > [1] commit 172b2386ed16 ("KVM: x86: fix missed hardware breakpoints") > [2] commit 70e4da7a8ff6 ("KVM: x86: fix root cause for missed hardware breakpoints") > > but this is the order for linux-4.4.y > > [1] commit fc90441e728a ("KVM: x86: fix missed hardware breakpoints") > [2] commit 25e8618619a5 ("KVM: x86: fix root cause for missed hardware breakpoints") > [0] commit 0f6e5e26e68f ("KVM: x86: fix missed hardware breakpoints") > > The upshot is that KVM_DEBUGREG_RELOAD is always set when returning > from kvm_arch_vcpu_load() in stable, but not in Linus' tree. How would applying these in a different order cause breakage? And if this is a problem, can you please send me a patch to fix it up? thanks, greg k-h ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: KVM patches applied in weird order in -stable 2016-09-13 14:58 ` KVM patches applied in weird order in -stable Greg KH @ 2016-09-13 16:26 ` Paolo Bonzini 2016-09-13 16:57 ` Greg KH 0 siblings, 1 reply; 5+ messages in thread From: Paolo Bonzini @ 2016-09-13 16:26 UTC (permalink / raw) To: Greg KH, Matt Fleming; +Cc: linux-kernel, stable On 13/09/2016 16:58, Greg KH wrote: > [adding stable@ as this is a stable issue, not a 'normal' issue] > > On Tue, Sep 13, 2016 at 03:51:00PM +0100, Matt Fleming wrote: >> Folks, >> >> While hunting down a performance issue involving KVM I was surprised >> to see "native_set_debugreg()" as the first entry in `perf top`. >> >> Digging deeper, it looks as though the following patches were applied >> in the wrong order in -stable. This is the order as they appear in >> Linus' tree, >> >> [0] commit 4e422bdd2f84 ("KVM: x86: fix missed hardware breakpoints") >> [1] commit 172b2386ed16 ("KVM: x86: fix missed hardware breakpoints") >> [2] commit 70e4da7a8ff6 ("KVM: x86: fix root cause for missed hardware breakpoints") >> >> but this is the order for linux-4.4.y >> >> [1] commit fc90441e728a ("KVM: x86: fix missed hardware breakpoints") >> [2] commit 25e8618619a5 ("KVM: x86: fix root cause for missed hardware breakpoints") >> [0] commit 0f6e5e26e68f ("KVM: x86: fix missed hardware breakpoints") >> >> The upshot is that KVM_DEBUGREG_RELOAD is always set when returning >> from kvm_arch_vcpu_load() in stable, but not in Linus' tree. > > How would applying these in a different order cause breakage? [2] is reverting [0]+[1]. Stable is not due to the different order. > And if this is a problem, can you please send me a patch to fix it up? Yup, on the way. Paolo ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: KVM patches applied in weird order in -stable 2016-09-13 16:26 ` Paolo Bonzini @ 2016-09-13 16:57 ` Greg KH 2016-09-13 16:58 ` Paolo Bonzini 0 siblings, 1 reply; 5+ messages in thread From: Greg KH @ 2016-09-13 16:57 UTC (permalink / raw) To: Paolo Bonzini; +Cc: Matt Fleming, linux-kernel, stable On Tue, Sep 13, 2016 at 06:26:12PM +0200, Paolo Bonzini wrote: > > > On 13/09/2016 16:58, Greg KH wrote: > > [adding stable@ as this is a stable issue, not a 'normal' issue] > > > > On Tue, Sep 13, 2016 at 03:51:00PM +0100, Matt Fleming wrote: > >> Folks, > >> > >> While hunting down a performance issue involving KVM I was surprised > >> to see "native_set_debugreg()" as the first entry in `perf top`. > >> > >> Digging deeper, it looks as though the following patches were applied > >> in the wrong order in -stable. This is the order as they appear in > >> Linus' tree, > >> > >> [0] commit 4e422bdd2f84 ("KVM: x86: fix missed hardware breakpoints") > >> [1] commit 172b2386ed16 ("KVM: x86: fix missed hardware breakpoints") > >> [2] commit 70e4da7a8ff6 ("KVM: x86: fix root cause for missed hardware breakpoints") > >> > >> but this is the order for linux-4.4.y > >> > >> [1] commit fc90441e728a ("KVM: x86: fix missed hardware breakpoints") > >> [2] commit 25e8618619a5 ("KVM: x86: fix root cause for missed hardware breakpoints") > >> [0] commit 0f6e5e26e68f ("KVM: x86: fix missed hardware breakpoints") > >> > >> The upshot is that KVM_DEBUGREG_RELOAD is always set when returning > >> from kvm_arch_vcpu_load() in stable, but not in Linus' tree. > > > > How would applying these in a different order cause breakage? > > [2] is reverting [0]+[1]. Stable is not due to the different order. Really? Are you sure that [0] and [1] isn't just the same commit? It looks like that to me. > > And if this is a problem, can you please send me a patch to fix it up? > > Yup, on the way. thanks, greg k-h ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: KVM patches applied in weird order in -stable 2016-09-13 16:57 ` Greg KH @ 2016-09-13 16:58 ` Paolo Bonzini 2016-09-14 1:19 ` Greg KH 0 siblings, 1 reply; 5+ messages in thread From: Paolo Bonzini @ 2016-09-13 16:58 UTC (permalink / raw) To: Greg KH; +Cc: Matt Fleming, linux-kernel, stable On 13/09/2016 18:57, Greg KH wrote: >>>> > >> [0] commit 4e422bdd2f84 ("KVM: x86: fix missed hardware breakpoints") >>>> > >> [1] commit 172b2386ed16 ("KVM: x86: fix missed hardware breakpoints") >>>> > >> [2] commit 70e4da7a8ff6 ("KVM: x86: fix root cause for missed hardware breakpoints") >>>> > >> >>>> > >> but this is the order for linux-4.4.y >>>> > >> >>>> > >> [1] commit fc90441e728a ("KVM: x86: fix missed hardware breakpoints") >>>> > >> [2] commit 25e8618619a5 ("KVM: x86: fix root cause for missed hardware breakpoints") >>>> > >> [0] commit 0f6e5e26e68f ("KVM: x86: fix missed hardware breakpoints") >>>> > >> >>>> > >> The upshot is that KVM_DEBUGREG_RELOAD is always set when returning >>>> > >> from kvm_arch_vcpu_load() in stable, but not in Linus' tree. >>> > > >>> > > How would applying these in a different order cause breakage? >> > >> > [2] is reverting [0]+[1]. Stable is not due to the different order. > Really? Are you sure that [0] and [1] isn't just the same commit? It > looks like that to me. It is; "git" automatically resolved the conflicts when merging [1], and then [2] reverted the change. In stable, changing the order created a different conflict resolution. Paolo ^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: KVM patches applied in weird order in -stable 2016-09-13 16:58 ` Paolo Bonzini @ 2016-09-14 1:19 ` Greg KH 0 siblings, 0 replies; 5+ messages in thread From: Greg KH @ 2016-09-14 1:19 UTC (permalink / raw) To: Paolo Bonzini; +Cc: Matt Fleming, linux-kernel, stable On Tue, Sep 13, 2016 at 06:58:40PM +0200, Paolo Bonzini wrote: > > > On 13/09/2016 18:57, Greg KH wrote: > >>>> > >> [0] commit 4e422bdd2f84 ("KVM: x86: fix missed hardware breakpoints") > >>>> > >> [1] commit 172b2386ed16 ("KVM: x86: fix missed hardware breakpoints") > >>>> > >> [2] commit 70e4da7a8ff6 ("KVM: x86: fix root cause for missed hardware breakpoints") > >>>> > >> > >>>> > >> but this is the order for linux-4.4.y > >>>> > >> > >>>> > >> [1] commit fc90441e728a ("KVM: x86: fix missed hardware breakpoints") > >>>> > >> [2] commit 25e8618619a5 ("KVM: x86: fix root cause for missed hardware breakpoints") > >>>> > >> [0] commit 0f6e5e26e68f ("KVM: x86: fix missed hardware breakpoints") > >>>> > >> > >>>> > >> The upshot is that KVM_DEBUGREG_RELOAD is always set when returning > >>>> > >> from kvm_arch_vcpu_load() in stable, but not in Linus' tree. > >>> > > > >>> > > How would applying these in a different order cause breakage? > >> > > >> > [2] is reverting [0]+[1]. Stable is not due to the different order. > > Really? Are you sure that [0] and [1] isn't just the same commit? It > > looks like that to me. > > It is; "git" automatically resolved the conflicts when merging [1], and > then [2] reverted the change. In stable, changing the order created a > different conflict resolution. Yes, given that I turn them into individual patches, the order I used was really the only one that would work, and is how this happened :) thanks, greg k-h ^ permalink raw reply [flat|nested] 5+ messages in thread
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2016-09-13 14:58 ` KVM patches applied in weird order in -stable Greg KH
2016-09-13 16:26 ` Paolo Bonzini
2016-09-13 16:57 ` Greg KH
2016-09-13 16:58 ` Paolo Bonzini
2016-09-14 1:19 ` Greg KH
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