From: Steve Capper <steve.capper@linaro.org>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux@arm.linux.org.uk" <linux@arm.linux.org.uk>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"gary.robertson@linaro.org" <gary.robertson@linaro.org>,
"anders.roxell@linaro.org" <anders.roxell@linaro.org>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>
Subject: Re: [RFC PATCH V4 6/7] arm64: mm: Enable HAVE_RCU_TABLE_FREE logic
Date: Thu, 1 May 2014 11:15:49 +0100 [thread overview]
Message-ID: <20140501101548.GA2254@linaro.org> (raw)
In-Reply-To: <20140501100415.GC22316@arm.com>
On Thu, May 01, 2014 at 11:04:15AM +0100, Catalin Marinas wrote:
> On Thu, May 01, 2014 at 10:57:39AM +0100, Peter Zijlstra wrote:
> > On Thu, May 01, 2014 at 10:52:47AM +0100, Catalin Marinas wrote:
> > > Does gup_fast walking increment the mm_users? Or is it a requirement of
> > > the calling code? I can't seem to find where this happens.
> >
> > No, its not required at all. One should only walk current->mm with
> > gup_fast, any other usage is broken.
>
> OK, I get it now.
>
> > And by delaying TLB shootdown, either through disabling IRQs and
> > stalling IPIs or by using RCU freeing, you're guaranteed your own page
> > tables won't disappear underneath your feet.
>
> And for RCU to work, we still need to use the full tlb_remove_table()
> logic (Steve's patches just use tlb_remove_page() for table freeing).
Yes, I see.
This is a bug in the arm64 patch (arm correctly calls tlb_remove_page),
I think it got ate during a rebase.
I will fix the arm64 activation logic.
Apologies for the confustion,
--
Steve
>
> Thanks.
>
> --
> Catalin
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
WARNING: multiple messages have this Message-ID (diff)
From: Steve Capper <steve.capper@linaro.org>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
"linux@arm.linux.org.uk" <linux@arm.linux.org.uk>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"gary.robertson@linaro.org" <gary.robertson@linaro.org>,
"anders.roxell@linaro.org" <anders.roxell@linaro.org>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>
Subject: Re: [RFC PATCH V4 6/7] arm64: mm: Enable HAVE_RCU_TABLE_FREE logic
Date: Thu, 1 May 2014 11:15:49 +0100 [thread overview]
Message-ID: <20140501101548.GA2254@linaro.org> (raw)
In-Reply-To: <20140501100415.GC22316@arm.com>
On Thu, May 01, 2014 at 11:04:15AM +0100, Catalin Marinas wrote:
> On Thu, May 01, 2014 at 10:57:39AM +0100, Peter Zijlstra wrote:
> > On Thu, May 01, 2014 at 10:52:47AM +0100, Catalin Marinas wrote:
> > > Does gup_fast walking increment the mm_users? Or is it a requirement of
> > > the calling code? I can't seem to find where this happens.
> >
> > No, its not required at all. One should only walk current->mm with
> > gup_fast, any other usage is broken.
>
> OK, I get it now.
>
> > And by delaying TLB shootdown, either through disabling IRQs and
> > stalling IPIs or by using RCU freeing, you're guaranteed your own page
> > tables won't disappear underneath your feet.
>
> And for RCU to work, we still need to use the full tlb_remove_table()
> logic (Steve's patches just use tlb_remove_page() for table freeing).
Yes, I see.
This is a bug in the arm64 patch (arm correctly calls tlb_remove_page),
I think it got ate during a rebase.
I will fix the arm64 activation logic.
Apologies for the confustion,
--
Steve
>
> Thanks.
>
> --
> Catalin
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
WARNING: multiple messages have this Message-ID (diff)
From: steve.capper@linaro.org (Steve Capper)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC PATCH V4 6/7] arm64: mm: Enable HAVE_RCU_TABLE_FREE logic
Date: Thu, 1 May 2014 11:15:49 +0100 [thread overview]
Message-ID: <20140501101548.GA2254@linaro.org> (raw)
In-Reply-To: <20140501100415.GC22316@arm.com>
On Thu, May 01, 2014 at 11:04:15AM +0100, Catalin Marinas wrote:
> On Thu, May 01, 2014 at 10:57:39AM +0100, Peter Zijlstra wrote:
> > On Thu, May 01, 2014 at 10:52:47AM +0100, Catalin Marinas wrote:
> > > Does gup_fast walking increment the mm_users? Or is it a requirement of
> > > the calling code? I can't seem to find where this happens.
> >
> > No, its not required at all. One should only walk current->mm with
> > gup_fast, any other usage is broken.
>
> OK, I get it now.
>
> > And by delaying TLB shootdown, either through disabling IRQs and
> > stalling IPIs or by using RCU freeing, you're guaranteed your own page
> > tables won't disappear underneath your feet.
>
> And for RCU to work, we still need to use the full tlb_remove_table()
> logic (Steve's patches just use tlb_remove_page() for table freeing).
Yes, I see.
This is a bug in the arm64 patch (arm correctly calls tlb_remove_page),
I think it got ate during a rebase.
I will fix the arm64 activation logic.
Apologies for the confustion,
--
Steve
>
> Thanks.
>
> --
> Catalin
>
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo at kvack.org. For more info on Linux MM,
> see: http://www.linux-mm.org/ .
> Don't email: <a href=mailto:"dont@kvack.org"> email at kvack.org </a>
next prev parent reply other threads:[~2014-05-01 10:15 UTC|newest]
Thread overview: 57+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-28 15:01 [RFC PATCH V4 0/7] get_user_pages_fast for ARM and ARM64 Steve Capper
2014-03-28 15:01 ` Steve Capper
2014-03-28 15:01 ` Steve Capper
2014-03-28 15:01 ` [RFC PATCH V4 1/7] mm: Introduce a general RCU get_user_pages_fast Steve Capper
2014-03-28 15:01 ` Steve Capper
2014-03-28 15:01 ` Steve Capper
2014-03-28 15:01 ` [RFC PATCH V4 2/7] arm: mm: Introduce special ptes for LPAE Steve Capper
2014-03-28 15:01 ` Steve Capper
2014-03-28 15:01 ` Steve Capper
2014-03-28 15:01 ` [RFC PATCH V4 3/7] arm: mm: Enable HAVE_RCU_TABLE_FREE logic Steve Capper
2014-03-28 15:01 ` Steve Capper
2014-03-28 15:01 ` Steve Capper
2014-05-01 11:11 ` Catalin Marinas
2014-05-01 11:11 ` Catalin Marinas
2014-05-01 11:11 ` Catalin Marinas
2014-05-01 11:44 ` Steve Capper
2014-05-01 11:44 ` Steve Capper
2014-05-01 11:44 ` Steve Capper
2014-03-28 15:01 ` [RFC PATCH V4 4/7] arm: mm: Enable RCU fast_gup Steve Capper
2014-03-28 15:01 ` Steve Capper
2014-03-28 15:01 ` Steve Capper
2014-03-28 15:01 ` [RFC PATCH V4 5/7] arm64: Convert asm/tlb.h to generic mmu_gather Steve Capper
2014-03-28 15:01 ` Steve Capper
2014-03-28 15:01 ` Steve Capper
2014-03-28 15:01 ` [RFC PATCH V4 6/7] arm64: mm: Enable HAVE_RCU_TABLE_FREE logic Steve Capper
2014-03-28 15:01 ` Steve Capper
2014-03-28 15:01 ` Steve Capper
2014-04-30 15:20 ` Catalin Marinas
2014-04-30 15:20 ` Catalin Marinas
2014-04-30 15:20 ` Catalin Marinas
2014-04-30 15:33 ` Catalin Marinas
2014-04-30 15:33 ` Catalin Marinas
2014-04-30 15:33 ` Catalin Marinas
2014-04-30 15:38 ` Steve Capper
2014-04-30 15:38 ` Steve Capper
2014-04-30 15:38 ` Steve Capper
2014-04-30 17:21 ` Catalin Marinas
2014-04-30 17:21 ` Catalin Marinas
2014-04-30 17:21 ` Catalin Marinas
2014-05-01 7:34 ` Steve Capper
2014-05-01 7:34 ` Steve Capper
2014-05-01 7:34 ` Steve Capper
2014-05-01 9:52 ` Catalin Marinas
2014-05-01 9:52 ` Catalin Marinas
2014-05-01 9:52 ` Catalin Marinas
2014-05-01 9:57 ` Peter Zijlstra
2014-05-01 9:57 ` Peter Zijlstra
2014-05-01 9:57 ` Peter Zijlstra
2014-05-01 10:04 ` Catalin Marinas
2014-05-01 10:04 ` Catalin Marinas
2014-05-01 10:04 ` Catalin Marinas
2014-05-01 10:15 ` Steve Capper [this message]
2014-05-01 10:15 ` Steve Capper
2014-05-01 10:15 ` Steve Capper
2014-03-28 15:01 ` [RFC PATCH V4 7/7] arm64: mm: Enable RCU fast_gup Steve Capper
2014-03-28 15:01 ` Steve Capper
2014-03-28 15:01 ` Steve Capper
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