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From: Linus Torvalds <torvalds@linux-foundation.org>
To: "Schimpe, Christina" <christina.schimpe@intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	 Andrew Morton <akpm@linux-foundation.org>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	 Kostya Serebryany <kcc@google.com>,
	Andrey Ryabinin <ryabinin.a.a@gmail.com>,
	 Andrey Konovalov <andreyknvl@gmail.com>,
	Alexander Potapenko <glider@google.com>,
	 Taras Madan <tarasmadan@google.com>,
	Dmitry Vyukov <dvyukov@google.com>,
	 "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	 "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	 "stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: Re: [PATCH] mm: Fix access_remote_vm() regression on tagged addresses
Date: Thu, 10 Aug 2023 11:39:12 -0700	[thread overview]
Message-ID: <CAHk-=whS19C=y32vNMRp7UfQMVw38HOfzhs9v5rjLayEFjMNPA@mail.gmail.com> (raw)
In-Reply-To: <CY4PR11MB2005976F49613E20BC072ECCF913A@CY4PR11MB2005.namprd11.prod.outlook.com>

On Thu, 10 Aug 2023 at 05:42, Schimpe, Christina
<christina.schimpe@intel.com> wrote:
>
> We don't have any LAM support in GDB yet, we are just working on it.
> We currently rely on that feature, but could still change it. We don't
> necessarily require /proc/PID/mem to support tagged addresses.
>
> ARM's TBI support in GDB does not rely on /proc/PID/mem to support tagged
> addresses AFAIK.

Ahh. That would explain why nobody noticed.

I do wonder if perhaps /proc/<pid>/mem should just match the real
addresses (ie the ones you would see in /proc/<pid>/maps).

The main reason GUP does the untagging is that obviously people will
pass in their own virtual addresses when doing direct-IO etc.

So /proc/<pid>/mem is a bit different.

That said, untagging does make some things easier, so I think it's
probably the right thing to do.

             Linus


      reply	other threads:[~2023-08-10 18:39 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-08-09 14:46 Kirill A. Shutemov
2023-08-09 15:05 ` Linus Torvalds
2023-08-10 12:42   ` Schimpe, Christina
2023-08-10 18:39     ` Linus Torvalds [this message]

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