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From: Thomas Gleixner <tglx@linutronix.de>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: LKML <linux-kernel@vger.kernel.org>,
	linux-arch <linux-arch@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
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	Matthew Wilcox <willy@infradead.org>
Subject: Re: [patch V2 00/18] mm/highmem: Preemptible variant of kmap_atomic & friends
Date: Sat, 31 Oct 2020 00:53:02 +0100	[thread overview]
Message-ID: <87mu03l19d.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <87pn4zl2ia.fsf@nanos.tec.linutronix.de>

On Sat, Oct 31 2020 at 00:26, Thomas Gleixner wrote:

> On Fri, Oct 30 2020 at 15:46, Linus Torvalds wrote:
>> On Fri, Oct 30, 2020 at 3:26 PM Thomas Gleixner <tglx@linutronix.de> wrote:
>> To me, your patch series has two big advantages:
>>
>>  - more common code
>>
>>  - kmap_local() becomes more of a no-op
>>
>> and the last thing we want is to expand on kmap.
>
> Happy to go with that.
>
> While trying to document the mess, I just stumbled over the abuse of
> kmap_atomic_prot() in
>
> drivers/gpu/drm/ttm/ttm_bo_util.c:      dst = kmap_atomic_prot(d, prot);
> drivers/gpu/drm/ttm/ttm_bo_util.c:      src = kmap_atomic_prot(s, prot);
> drivers/gpu/drm/vmwgfx/vmwgfx_blit.c:   kmap_atomic_prot(d->dst_pages[dst_page],
> drivers/gpu/drm/vmwgfx/vmwgfx_blit.c:   kmap_atomic_prot(d->src_pages[src_page],
>
> For !HIGHMEM kmap_atomic_prot() just ignores the 'prot' argument and
> returns the page address. 
>
> Moar patches to be written ... Sigh!

Or not. This is actually correct by some definition of correct. For
the non highmem case pgprot is set via the set_memory_*() functions and
this just handles the highmem case.

Comments are overrrated...

  reply	other threads:[~2020-10-30 23:53 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-29 22:18 [patch V2 00/18] mm/highmem: Preemptible variant of kmap_atomic & friends Thomas Gleixner
2020-10-29 22:18 ` [patch V2 01/18] sched: Make migrate_disable/enable() independent of RT Thomas Gleixner
2020-10-29 22:18 ` [patch V2 02/18] mm/highmem: Un-EXPORT __kmap_atomic_idx() Thomas Gleixner
2020-10-29 22:18 ` [patch V2 03/18] highmem: Provide generic variant of kmap_atomic* Thomas Gleixner
2020-10-29 22:18 ` [patch V2 04/18] x86/mm/highmem: Use generic kmap atomic implementation Thomas Gleixner
2020-10-29 22:18 ` [patch V2 05/18] arc/mm/highmem: " Thomas Gleixner
2020-10-29 22:18 ` [patch V2 06/18] ARM: highmem: Switch to generic kmap atomic Thomas Gleixner
2020-10-29 22:18 ` [patch V2 07/18] csky/mm/highmem: " Thomas Gleixner
2020-10-29 22:18 ` [patch V2 08/18] microblaze/mm/highmem: " Thomas Gleixner
2020-10-29 22:18 ` [patch V2 09/18] mips/mm/highmem: " Thomas Gleixner
2020-10-29 22:18 ` [patch V2 10/18] nds32/mm/highmem: " Thomas Gleixner
2020-10-29 22:18 ` [patch V2 11/18] powerpc/mm/highmem: " Thomas Gleixner
2020-10-29 22:18 ` [patch V2 12/18] sparc/mm/highmem: " Thomas Gleixner
2020-10-29 22:18 ` [patch V2 13/18] xtensa/mm/highmem: " Thomas Gleixner
2020-10-29 22:18 ` [patch V2 14/18] mm/highmem: Remove the old kmap_atomic cruft Thomas Gleixner
2020-10-29 22:18 ` [patch V2 15/18] io-mapping: Cleanup atomic iomap Thomas Gleixner
2020-10-29 22:18 ` [patch V2 16/18] sched: highmem: Store local kmaps in task struct Thomas Gleixner
2020-10-29 22:18 ` [patch V2 17/18] mm/highmem: Provide kmap_local* Thomas Gleixner
2020-10-29 22:18 ` [patch V2 18/18] io-mapping: Provide iomap_local variant Thomas Gleixner
2020-10-29 23:11 ` [patch V2 00/18] mm/highmem: Preemptible variant of kmap_atomic & friends Linus Torvalds
2020-10-29 23:41   ` Thomas Gleixner
2020-10-30  9:39     ` Thomas Gleixner
2020-10-30 20:28       ` Linus Torvalds
2020-10-30 22:26         ` Thomas Gleixner
2020-10-30 22:46           ` Linus Torvalds
2020-10-30 23:26             ` Thomas Gleixner
2020-10-30 23:53               ` Thomas Gleixner [this message]
2020-10-31 13:37             ` Arnd Bergmann
2020-10-31 15:05               ` Christophe Leroy
2020-10-31 21:33                 ` Arnd Bergmann
2020-10-30  7:25 ` Christoph Hellwig
2020-10-30  9:39   ` Thomas Gleixner
2020-10-30 13:06 ` Matthew Wilcox
2020-10-30 19:35   ` Thomas Gleixner
2020-11-02  1:08 ` Thomas Gleixner

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