* [PATCH] mm: Always print RLIMIT_DATA warning
@ 2018-02-06 16:45 ` David Woodhouse
0 siblings, 0 replies; 8+ messages in thread
From: David Woodhouse @ 2018-02-06 16:45 UTC (permalink / raw)
To: Konstantin Khlebnikov, Andrew Morton, Cyrill Gorcunov,
Linus Torvalds, Vegard Nossum, Peter Zijlstra, Vladimir Davydov,
Andy Lutomirski, Quentin Casasnovas, Kees Cook, Willy Tarreau,
Pavel Emelyanov, Laura Abbott, linux-kernel, linux-mm
The documentation for ignore_rlimit_data says that it will print a warning
at first misuse. Yet it doesn't seem to do that. Fix the code to print
the warning even when we allow the process to continue.
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
---
We should probably also do what Linus suggested in
https://lkml.org/lkml/2016/9/16/585
mm/mmap.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
diff --git a/mm/mmap.c b/mm/mmap.c
index 9efdc021..dd76ea3 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3184,13 +3184,15 @@ bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
if (rlimit(RLIMIT_DATA) == 0 &&
mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT)
return true;
- if (!ignore_rlimit_data) {
- pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits or use boot option ignore_rlimit_data.\n",
- current->comm, current->pid,
- (mm->data_vm + npages) << PAGE_SHIFT,
- rlimit(RLIMIT_DATA));
+
+ pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n",
+ current->comm, current->pid,
+ (mm->data_vm + npages) << PAGE_SHIFT,
+ rlimit(RLIMIT_DATA),
+ ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data");
+
+ if (!ignore_rlimit_data)
return false;
- }
}
return true;
--
2.7.4
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^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH] mm: Always print RLIMIT_DATA warning
2018-02-06 16:45 ` David Woodhouse
@ 2018-02-06 17:27 ` Cyrill Gorcunov
-1 siblings, 0 replies; 8+ messages in thread
From: Cyrill Gorcunov @ 2018-02-06 17:27 UTC (permalink / raw)
To: David Woodhouse
Cc: Konstantin Khlebnikov, Andrew Morton, Linus Torvalds,
Vegard Nossum, Peter Zijlstra, Vladimir Davydov, Andy Lutomirski,
Quentin Casasnovas, Kees Cook, Willy Tarreau, Pavel Emelyanov,
Laura Abbott, linux-kernel, linux-mm
On Tue, Feb 06, 2018 at 04:45:05PM +0000, David Woodhouse wrote:
> The documentation for ignore_rlimit_data says that it will print a warning
> at first misuse. Yet it doesn't seem to do that. Fix the code to print
> the warning even when we allow the process to continue.
>
> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> ---
> We should probably also do what Linus suggested in
> https://lkml.org/lkml/2016/9/16/585
>
Might be typo in docs I guess, Kostya?
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] mm: Always print RLIMIT_DATA warning
@ 2018-02-06 17:27 ` Cyrill Gorcunov
0 siblings, 0 replies; 8+ messages in thread
From: Cyrill Gorcunov @ 2018-02-06 17:27 UTC (permalink / raw)
To: David Woodhouse
Cc: Konstantin Khlebnikov, Andrew Morton, Linus Torvalds,
Vegard Nossum, Peter Zijlstra, Vladimir Davydov, Andy Lutomirski,
Quentin Casasnovas, Kees Cook, Willy Tarreau, Pavel Emelyanov,
Laura Abbott, linux-kernel, linux-mm
On Tue, Feb 06, 2018 at 04:45:05PM +0000, David Woodhouse wrote:
> The documentation for ignore_rlimit_data says that it will print a warning
> at first misuse. Yet it doesn't seem to do that. Fix the code to print
> the warning even when we allow the process to continue.
>
> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> ---
> We should probably also do what Linus suggested in
> https://lkml.org/lkml/2016/9/16/585
>
Might be typo in docs I guess, Kostya?
--
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^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] mm: Always print RLIMIT_DATA warning
2018-02-06 17:27 ` Cyrill Gorcunov
(?)
@ 2018-02-06 17:30 ` David Woodhouse
-1 siblings, 0 replies; 8+ messages in thread
From: David Woodhouse @ 2018-02-06 17:30 UTC (permalink / raw)
To: Cyrill Gorcunov
Cc: Konstantin Khlebnikov, Andrew Morton, Linus Torvalds,
Vegard Nossum, Peter Zijlstra, Vladimir Davydov, Andy Lutomirski,
Quentin Casasnovas, Kees Cook, Willy Tarreau, Pavel Emelyanov,
Laura Abbott, linux-kernel, linux-mm
[-- Attachment #1: Type: text/plain, Size: 634 bytes --]
On Tue, 2018-02-06 at 20:27 +0300, Cyrill Gorcunov wrote:
> On Tue, Feb 06, 2018 at 04:45:05PM +0000, David Woodhouse wrote:
> >
> > The documentation for ignore_rlimit_data says that it will print a warning
> > at first misuse. Yet it doesn't seem to do that. Fix the code to print
> > the warning even when we allow the process to continue.
> >
> > Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> > ---
> > We should probably also do what Linus suggested in
> > https://lkml.org/lkml/2016/9/16/585
> >
> Might be typo in docs I guess, Kostya?
I prefer the documented behaviour to the actual behaviour :)
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^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] mm: Always print RLIMIT_DATA warning
2018-02-06 16:45 ` David Woodhouse
@ 2018-02-06 17:48 ` Konstantin Khlebnikov
-1 siblings, 0 replies; 8+ messages in thread
From: Konstantin Khlebnikov @ 2018-02-06 17:48 UTC (permalink / raw)
To: David Woodhouse
Cc: Andrew Morton, Cyrill Gorcunov, Linus Torvalds, Vegard Nossum,
Peter Zijlstra, Vladimir Davydov, Andy Lutomirski,
Quentin Casasnovas, Kees Cook, Willy Tarreau, Pavel Emelyanov,
Laura Abbott, Linux Kernel Mailing List, linux-mm
On Tue, Feb 6, 2018 at 7:45 PM, David Woodhouse <dwmw@amazon.co.uk> wrote:
> The documentation for ignore_rlimit_data says that it will print a warning
> at first misuse. Yet it doesn't seem to do that. Fix the code to print
> the warning even when we allow the process to continue.
Ack. But I think this was a misprint in docs.
Anyway, this knob is a kludge so we might warn once even if it is set.
So, somebody still have problems with this change?
I remember concerns about that "warn_once" isn't enough to detect
what's going wrong.
And probably we should invent "warn_sometimes".
>
> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> ---
> We should probably also do what Linus suggested in
> https://lkml.org/lkml/2016/9/16/585
>
> mm/mmap.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 9efdc021..dd76ea3 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -3184,13 +3184,15 @@ bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
> if (rlimit(RLIMIT_DATA) == 0 &&
> mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT)
> return true;
> - if (!ignore_rlimit_data) {
> - pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits or use boot option ignore_rlimit_data.\n",
> - current->comm, current->pid,
> - (mm->data_vm + npages) << PAGE_SHIFT,
> - rlimit(RLIMIT_DATA));
> +
> + pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n",
> + current->comm, current->pid,
> + (mm->data_vm + npages) << PAGE_SHIFT,
> + rlimit(RLIMIT_DATA),
> + ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data");
> +
> + if (!ignore_rlimit_data)
> return false;
> - }
> }
>
> return true;
> --
> 2.7.4
>
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] mm: Always print RLIMIT_DATA warning
@ 2018-02-06 17:48 ` Konstantin Khlebnikov
0 siblings, 0 replies; 8+ messages in thread
From: Konstantin Khlebnikov @ 2018-02-06 17:48 UTC (permalink / raw)
To: David Woodhouse
Cc: Andrew Morton, Cyrill Gorcunov, Linus Torvalds, Vegard Nossum,
Peter Zijlstra, Vladimir Davydov, Andy Lutomirski,
Quentin Casasnovas, Kees Cook, Willy Tarreau, Pavel Emelyanov,
Laura Abbott, Linux Kernel Mailing List, linux-mm
On Tue, Feb 6, 2018 at 7:45 PM, David Woodhouse <dwmw@amazon.co.uk> wrote:
> The documentation for ignore_rlimit_data says that it will print a warning
> at first misuse. Yet it doesn't seem to do that. Fix the code to print
> the warning even when we allow the process to continue.
Ack. But I think this was a misprint in docs.
Anyway, this knob is a kludge so we might warn once even if it is set.
So, somebody still have problems with this change?
I remember concerns about that "warn_once" isn't enough to detect
what's going wrong.
And probably we should invent "warn_sometimes".
>
> Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
> ---
> We should probably also do what Linus suggested in
> https://lkml.org/lkml/2016/9/16/585
>
> mm/mmap.c | 14 ++++++++------
> 1 file changed, 8 insertions(+), 6 deletions(-)
>
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 9efdc021..dd76ea3 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -3184,13 +3184,15 @@ bool may_expand_vm(struct mm_struct *mm, vm_flags_t flags, unsigned long npages)
> if (rlimit(RLIMIT_DATA) == 0 &&
> mm->data_vm + npages <= rlimit_max(RLIMIT_DATA) >> PAGE_SHIFT)
> return true;
> - if (!ignore_rlimit_data) {
> - pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits or use boot option ignore_rlimit_data.\n",
> - current->comm, current->pid,
> - (mm->data_vm + npages) << PAGE_SHIFT,
> - rlimit(RLIMIT_DATA));
> +
> + pr_warn_once("%s (%d): VmData %lu exceed data ulimit %lu. Update limits%s.\n",
> + current->comm, current->pid,
> + (mm->data_vm + npages) << PAGE_SHIFT,
> + rlimit(RLIMIT_DATA),
> + ignore_rlimit_data ? "" : " or use boot option ignore_rlimit_data");
> +
> + if (!ignore_rlimit_data)
> return false;
> - }
> }
>
> return true;
> --
> 2.7.4
>
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^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] mm: Always print RLIMIT_DATA warning
2018-02-06 17:48 ` Konstantin Khlebnikov
(?)
@ 2018-02-07 13:03 ` David Woodhouse
-1 siblings, 0 replies; 8+ messages in thread
From: David Woodhouse @ 2018-02-07 13:03 UTC (permalink / raw)
To: Konstantin Khlebnikov
Cc: Andrew Morton, Cyrill Gorcunov, Linus Torvalds, Vegard Nossum,
Peter Zijlstra, Vladimir Davydov, Andy Lutomirski,
Quentin Casasnovas, Kees Cook, Willy Tarreau, Pavel Emelyanov,
Laura Abbott, Linux Kernel Mailing List, linux-mm
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On Tue, 2018-02-06 at 20:48 +0300, Konstantin Khlebnikov wrote:
> On Tue, Feb 6, 2018 at 7:45 PM, David Woodhouse <dwmw@amazon.co.uk> wrote:
> >
> > The documentation for ignore_rlimit_data says that it will print a warning
> > at first misuse. Yet it doesn't seem to do that. Fix the code to print
> > the warning even when we allow the process to continue.
>
> Ack. But I think this was a misprint in docs.
> Anyway, this knob is a kludge so we might warn once even if it is set.
Right. I think we definitely should. Otherwise, once set, there's no
real path to ever being able to *unset* it. Nothing well ever get
fixed.
> So, somebody still have problems with this change?
> I remember concerns about that "warn_once" isn't enough to detect
> what's going wrong.
> And probably we should invent "warn_sometimes".
That was covered by "should probably also do what Linus suggested…":
> > ---
> > We should probably also do what Linus suggested in
> > https://lkml.org/lkml/2016/9/16/585
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^ permalink raw reply [flat|nested] 8+ messages in thread