On Wed, Jul 27, 2011 at 06:17, Peter Zijlstra wrote:
> On Wed, 2011-07-27 at 11:09 +0100, David Howells wrote:
>> Can you inline this for the NOMMU case please?
>
> ---
> Subject: mm: Fix fixup_user_fault() for MMU=n
>
> In commit 2efaca927 ("mm/futex: fix futex writes on archs with SW
> tracking o
Peter Zijlstra wrote:
> Subject: mm: Fix fixup_user_fault() for MMU=n
>
> In commit 2efaca927 ("mm/futex: fix futex writes on archs with SW
> tracking of dirty & young") we forgot about MMU=n. This patch fixes
> that.
>
> Signed-off-by: Peter Zijlstra
Acked-by: David Howells
___
On Wed, Jul 27, 2011 at 03:20, Benjamin Herrenschmidt wrote:
> Hoping the BUG() isn't trippable by userspace but then it's no mmu, it's
> not like we care what userspace can do right :-)
side note ... common misconception that "no mmu" == "no memory
protection". a few of the nommu processors have
On Wed, 2011-07-27 at 12:17 +0200, Peter Zijlstra wrote:
> On Wed, 2011-07-27 at 11:09 +0100, David Howells wrote:
> > Can you inline this for the NOMMU case please?
>
> ---
> Subject: mm: Fix fixup_user_fault() for MMU=n
>
> In commit 2efaca927 ("mm/futex: fix futex writes on archs with SW
> tr
On Wed, 2011-07-27 at 11:09 +0100, David Howells wrote:
> Can you inline this for the NOMMU case please?
---
Subject: mm: Fix fixup_user_fault() for MMU=n
In commit 2efaca927 ("mm/futex: fix futex writes on archs with SW
tracking of dirty & young") we forgot about MMU=n. This patch fixes
that.
Peter Zijlstra wrote:
> > What should nommu do anyways ? it's not like there's much it can do
> > right ? It should never even hit the fault path to start with ...
>
> Something like the below makes a nommu arm config build.. David, is this
> indeed the correct thing to do for nommu?
>
> ---
>
On Wed, 2011-07-27 at 17:58 +1000, Benjamin Herrenschmidt wrote:
> What should nommu do anyways ? it's not like there's much it can do
> right ? It should never even hit the fault path to start with ...
Something like the below makes a nommu arm config build.. David, is this
indeed the correct th
On Tue, 2011-07-26 at 23:50 -0700, Mike Frysinger wrote:
> On Mon, Jul 18, 2011 at 21:29, Benjamin Herrenschmidt wrote:
> > The futex code currently attempts to write to user memory within
> > a pagefault disabled section, and if that fails, tries to fix it
> > up using get_user_pages().
> >
> > Th
On Mon, Jul 18, 2011 at 21:29, Benjamin Herrenschmidt wrote:
> The futex code currently attempts to write to user memory within
> a pagefault disabled section, and if that fails, tries to fix it
> up using get_user_pages().
>
> This doesn't work on archs where the dirty and young bits are
> maintai
On 07/22/2011 06:59 AM, Andrew Morton wrote:
On Fri, 22 Jul 2011 08:52:06 +1000
Benjamin Herrenschmidt wrote:
On Thu, 2011-07-21 at 15:36 -0700, Andrew Morton wrote:
On Tue, 19 Jul 2011 14:29:22 +1000
Benjamin Herrenschmidt wrote:
The futex code currently attempts to write to user memory w
> You're not understanding me.
>
> I need a good reason to merge this into 3.0.
>
> The -stable maintainers need even better reasons to merge this into
> earlier kernels.
>
> Please provide those reasons!
>
> (Documentation/stable_kernel_rules.txt, 4th bullet)
>
> (And it's not just me and -s
On Fri, 22 Jul 2011 08:52:06 +1000
Benjamin Herrenschmidt wrote:
> On Thu, 2011-07-21 at 15:36 -0700, Andrew Morton wrote:
> > On Tue, 19 Jul 2011 14:29:22 +1000
> > Benjamin Herrenschmidt wrote:
> >
> > > The futex code currently attempts to write to user memory within
> > > a pagefault disabl
On Fri, 2011-07-22 at 08:52 +1000, Benjamin Herrenschmidt wrote:
> > um, what problem. There's no description here of the user-visible
> > effects of the bug hence it's hard to work out what kernel version(s)
> > should receive this patch.
>
> Shan could give you an actual example (it was in the
On Thu, 2011-07-21 at 15:36 -0700, Andrew Morton wrote:
> On Tue, 19 Jul 2011 14:29:22 +1000
> Benjamin Herrenschmidt wrote:
>
> > The futex code currently attempts to write to user memory within
> > a pagefault disabled section, and if that fails, tries to fix it
> > up using get_user_pages().
>
On Tue, 19 Jul 2011 14:29:22 +1000
Benjamin Herrenschmidt wrote:
> The futex code currently attempts to write to user memory within
> a pagefault disabled section, and if that fails, tries to fix it
> up using get_user_pages().
>
> This doesn't work on archs where the dirty and young bits are
>
Obviously no objection from the futex side of things, looks good. Couple
nits on the function comment:
On 07/18/2011 09:29 PM, Benjamin Herrenschmidt wrote:
...
> -/**
> +/*
> + * fixup_user_fault() - manually resolve a user page fault
s/ fault/ fault/
> + * @tsk: the task_struct to use fo
On Tue, 2011-07-19 at 14:29 +1000, Benjamin Herrenschmidt wrote:
> The futex code currently attempts to write to user memory within
> a pagefault disabled section, and if that fails, tries to fix it
> up using get_user_pages().
>
> This doesn't work on archs where the dirty and young bits are
> ma
On 07/19/2011 03:46 PM, Benjamin Herrenschmidt wrote:
On Tue, 2011-07-19 at 13:38 +0800, Shan Hai wrote:
What you said is another path, that is futex_wake_op(),
but what about futex_lock_pi in which my test case failed?
your patch will call handle_mm_fault on every futex contention
in the futex
On Tue, 2011-07-19 at 13:38 +0800, Shan Hai wrote:
> What you said is another path, that is futex_wake_op(),
> but what about futex_lock_pi in which my test case failed?
> your patch will call handle_mm_fault on every futex contention
> in the futex_lock_pi path.
>
> futex_lock_pi()
> ret =
On 07/19/2011 01:24 PM, Benjamin Herrenschmidt wrote:
On Tue, 2011-07-19 at 13:17 +0800, Shan Hai wrote:
The patch works, but I have certain confusions,
- Do we want to handle_mm_fault on each futex_lock_pi
even though in most cases there is no write permission
fixup's needed?
Don'
On Tue, 2011-07-19 at 13:17 +0800, Shan Hai wrote:
> The patch works, but I have certain confusions,
> - Do we want to handle_mm_fault on each futex_lock_pi
> even though in most cases there is no write permission
> fixup's needed?
Don't we only ever call this when futex_atomic_op_inuse
On 07/19/2011 12:29 PM, Benjamin Herrenschmidt wrote:
The futex code currently attempts to write to user memory within
a pagefault disabled section, and if that fails, tries to fix it
up using get_user_pages().
This doesn't work on archs where the dirty and young bits are
maintained by software,
On 07/19/2011 12:29 PM, Benjamin Herrenschmidt wrote:
The futex code currently attempts to write to user memory within
a pagefault disabled section, and if that fails, tries to fix it
up using get_user_pages().
This doesn't work on archs where the dirty and young bits are
maintained by software,
The futex code currently attempts to write to user memory within
a pagefault disabled section, and if that fails, tries to fix it
up using get_user_pages().
This doesn't work on archs where the dirty and young bits are
maintained by software, since they will gate access permission
in the TLB, and
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