* [PATCH] x86/mm: Remove in_nmi() warning from 64bit implementation of vmalloc_fault()
@ 2019-04-24 7:04 Jiri Kosina
2019-04-24 7:26 ` Peter Zijlstra
2019-04-24 11:11 ` [tip:x86/mm] x86/mm: Remove in_nmi() warning from 64-bit " tip-bot for Jiri Kosina
0 siblings, 2 replies; 4+ messages in thread
From: Jiri Kosina @ 2019-04-24 7:04 UTC (permalink / raw)
To: Dave Hansen, Andy Lutomirski, Peter Zijlstra, Thomas Gleixner,
Ingo Molnar, Borislav Petkov, H. Peter Anvin
Cc: Joerg Roedel, Frederic Weisbecker, Nicolai Stange, x86, linux-kernel
From: Jiri Kosina <jkosina@suse.cz>
In-NMI warnings have been added to vmalloc_fault() via ebc8827f75 ("x86:
Barf when vmalloc and kmemcheck faults happen in NMI") back in the time
when our NMI entry code could not cope with nested NMIs.
These days, it's perfectly fine to take a fault in NMI context and we
don't have to care about the fact that IRET from the fault handler might
cause NMI nesting.
This warning has already been removed from 32bit implementation of
vmalloc_fault() in 6863ea0cda8 ("x86/mm: Remove in_nmi() warning from
vmalloc_fault()"), but 64bit version was omitted.
Remove the bogus warning also from 64bit implementation of vmalloc_fault().
Fixes: 6863ea0cda8 ("x86/mm: Remove in_nmi() warning from vmalloc_fault()")
Reported-by: Nicolai Stange <nstange@suse.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
---
arch/x86/mm/fault.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index 667f1da36208..5eaf67e8314f 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -359,8 +359,6 @@ static noinline int vmalloc_fault(unsigned long address)
if (!(address >= VMALLOC_START && address < VMALLOC_END))
return -1;
- WARN_ON_ONCE(in_nmi());
-
/*
* Copy kernel mappings over when needed. This can also
* happen within a race in page table update. In the later
--
Jiri Kosina
SUSE Labs
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] x86/mm: Remove in_nmi() warning from 64bit implementation of vmalloc_fault()
2019-04-24 7:04 [PATCH] x86/mm: Remove in_nmi() warning from 64bit implementation of vmalloc_fault() Jiri Kosina
@ 2019-04-24 7:26 ` Peter Zijlstra
2019-04-24 7:31 ` Jiri Kosina
2019-04-24 11:11 ` [tip:x86/mm] x86/mm: Remove in_nmi() warning from 64-bit " tip-bot for Jiri Kosina
1 sibling, 1 reply; 4+ messages in thread
From: Peter Zijlstra @ 2019-04-24 7:26 UTC (permalink / raw)
To: Jiri Kosina
Cc: Dave Hansen, Andy Lutomirski, Thomas Gleixner, Ingo Molnar,
Borislav Petkov, H. Peter Anvin, Joerg Roedel,
Frederic Weisbecker, Nicolai Stange, x86, linux-kernel
On Wed, Apr 24, 2019 at 09:04:57AM +0200, Jiri Kosina wrote:
> From: Jiri Kosina <jkosina@suse.cz>
>
> In-NMI warnings have been added to vmalloc_fault() via ebc8827f75 ("x86:
> Barf when vmalloc and kmemcheck faults happen in NMI") back in the time
> when our NMI entry code could not cope with nested NMIs.
>
> These days, it's perfectly fine to take a fault in NMI context and we
> don't have to care about the fact that IRET from the fault handler might
> cause NMI nesting.
>
> This warning has already been removed from 32bit implementation of
> vmalloc_fault() in 6863ea0cda8 ("x86/mm: Remove in_nmi() warning from
> vmalloc_fault()"), but 64bit version was omitted.
>
> Remove the bogus warning also from 64bit implementation of vmalloc_fault().
Cute; did you actually trigger this?
> Fixes: 6863ea0cda8 ("x86/mm: Remove in_nmi() warning from vmalloc_fault()")
> Reported-by: Nicolai Stange <nstange@suse.de>
> Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
> ---
> arch/x86/mm/fault.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
> index 667f1da36208..5eaf67e8314f 100644
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -359,8 +359,6 @@ static noinline int vmalloc_fault(unsigned long address)
> if (!(address >= VMALLOC_START && address < VMALLOC_END))
> return -1;
>
> - WARN_ON_ONCE(in_nmi());
> -
> /*
> * Copy kernel mappings over when needed. This can also
> * happen within a race in page table update. In the later
>
> --
> Jiri Kosina
> SUSE Labs
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] x86/mm: Remove in_nmi() warning from 64bit implementation of vmalloc_fault()
2019-04-24 7:26 ` Peter Zijlstra
@ 2019-04-24 7:31 ` Jiri Kosina
0 siblings, 0 replies; 4+ messages in thread
From: Jiri Kosina @ 2019-04-24 7:31 UTC (permalink / raw)
To: Peter Zijlstra
Cc: Dave Hansen, Andy Lutomirski, Thomas Gleixner, Ingo Molnar,
Borislav Petkov, H. Peter Anvin, Joerg Roedel,
Frederic Weisbecker, Nicolai Stange, x86, linux-kernel
On Wed, 24 Apr 2019, Peter Zijlstra wrote:
> > In-NMI warnings have been added to vmalloc_fault() via ebc8827f75 ("x86:
> > Barf when vmalloc and kmemcheck faults happen in NMI") back in the time
> > when our NMI entry code could not cope with nested NMIs.
> >
> > These days, it's perfectly fine to take a fault in NMI context and we
> > don't have to care about the fact that IRET from the fault handler might
> > cause NMI nesting.
> >
> > This warning has already been removed from 32bit implementation of
> > vmalloc_fault() in 6863ea0cda8 ("x86/mm: Remove in_nmi() warning from
> > vmalloc_fault()"), but 64bit version was omitted.
> >
> > Remove the bogus warning also from 64bit implementation of vmalloc_fault().
>
> Cute; did you actually trigger this?
Nope; Nicolai tripped over it while he was looking into interactions
between ftrace and pagefaults.
> > Fixes: 6863ea0cda8 ("x86/mm: Remove in_nmi() warning from vmalloc_fault()")
> > Reported-by: Nicolai Stange <nstange@suse.de>
> > Signed-off-by: Jiri Kosina <jkosina@suse.cz>
>
> Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Thanks,
--
Jiri Kosina
SUSE Labs
^ permalink raw reply [flat|nested] 4+ messages in thread
* [tip:x86/mm] x86/mm: Remove in_nmi() warning from 64-bit implementation of vmalloc_fault()
2019-04-24 7:04 [PATCH] x86/mm: Remove in_nmi() warning from 64bit implementation of vmalloc_fault() Jiri Kosina
2019-04-24 7:26 ` Peter Zijlstra
@ 2019-04-24 11:11 ` tip-bot for Jiri Kosina
1 sibling, 0 replies; 4+ messages in thread
From: tip-bot for Jiri Kosina @ 2019-04-24 11:11 UTC (permalink / raw)
To: linux-tip-commits
Cc: dave.hansen, peterz, torvalds, luto, jkosina, linux-kernel,
mingo, tglx, jroedel, nstange, bp, fweisbec, hpa
Commit-ID: a65c88e16f32aa9ef2e8caa68ea5c29bd5eb0ff0
Gitweb: https://git.kernel.org/tip/a65c88e16f32aa9ef2e8caa68ea5c29bd5eb0ff0
Author: Jiri Kosina <jkosina@suse.cz>
AuthorDate: Wed, 24 Apr 2019 09:04:57 +0200
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 24 Apr 2019 12:21:35 +0200
x86/mm: Remove in_nmi() warning from 64-bit implementation of vmalloc_fault()
In-NMI warnings have been added to vmalloc_fault() via:
ebc8827f75 ("x86: Barf when vmalloc and kmemcheck faults happen in NMI")
back in the time when our NMI entry code could not cope with nested NMIs.
These days, it's perfectly fine to take a fault in NMI context and we
don't have to care about the fact that IRET from the fault handler might
cause NMI nesting.
This warning has already been removed from 32-bit implementation of
vmalloc_fault() in:
6863ea0cda8 ("x86/mm: Remove in_nmi() warning from vmalloc_fault()")
but the 64-bit version was omitted.
Remove the bogus warning also from 64-bit implementation of vmalloc_fault().
Reported-by: Nicolai Stange <nstange@suse.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 6863ea0cda8 ("x86/mm: Remove in_nmi() warning from vmalloc_fault()")
Link: http://lkml.kernel.org/r/nycvar.YFH.7.76.1904240902280.9803@cbobk.fhfr.pm
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/mm/fault.c | 2 --
1 file changed, 2 deletions(-)
diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index a0df19b0897d..bd20de9db1a8 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c
@@ -359,8 +359,6 @@ static noinline int vmalloc_fault(unsigned long address)
if (!(address >= VMALLOC_START && address < VMALLOC_END))
return -1;
- WARN_ON_ONCE(in_nmi());
-
/*
* Copy kernel mappings over when needed. This can also
* happen within a race in page table update. In the later
^ permalink raw reply related [flat|nested] 4+ messages in thread
end of thread, other threads:[~2019-04-24 11:11 UTC | newest]
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2019-04-24 7:04 [PATCH] x86/mm: Remove in_nmi() warning from 64bit implementation of vmalloc_fault() Jiri Kosina
2019-04-24 7:26 ` Peter Zijlstra
2019-04-24 7:31 ` Jiri Kosina
2019-04-24 11:11 ` [tip:x86/mm] x86/mm: Remove in_nmi() warning from 64-bit " tip-bot for Jiri Kosina
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