From: Matthew Wilcox <willy@infradead.org>
To: Peter Xu <peterx@redhat.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
linux-arm-kernel@lists.infradead.org, linux-s390@vger.kernel.org
Subject: Re: [PATCH 0/3] mm/arch: Fix a few collide definition on private use of VM_FAULT_*
Date: Mon, 6 Feb 2023 05:09:57 +0000 [thread overview]
Message-ID: <Y+CLpdnOGFg28uMJ@casper.infradead.org> (raw)
In-Reply-To: <Y+BxhuGUx1K+3XHb@xz-m1.local>
On Sun, Feb 05, 2023 at 10:18:30PM -0500, Peter Xu wrote:
> On Mon, Feb 06, 2023 at 02:51:18AM +0000, Matthew Wilcox wrote:
> > That wasn't what I meant. I meant putting VM_FAULT_BADMAP and
> > VM_FAULT_SIGSEGV in mm_types.h. Not having "Here is a range of reserved
> > arch private ones".
>
> VM_FAULT_SIGSEGV is there already; I assume you meant adding them all
> directly into vm_fault_reason.
>
> Then I don't think it's a good idea..
>
> Currently vm_fault_reason is a clear interface for handle_mm_fault() for
> not only arch pffault handlers but also soft faults like GUP.
>
> If handle_mm_fault() doesn't return VM_FAULT_BADMAP at all, I don't think
> we should have it as public API at all. When arch1 people reading the
> VM_FAULT_ documents, it shouldn't care about some fault reason that only
> happens with arch2. Gup shouldn't care about it either.
>
> Logically a new page fault handler should handle all the retval of
> vm_fault_reason afaiu. That shouldn't include e.g. VM_FAULT_BADMAP either.
Hmm, right. Looking specifically at how s390 uses VM_FAULT_BADMAP,
it just seems to be a badly structured fault.c. Seems to me that
do_fault_error() should take an extra si_code argument, and
instead of returning VM_FAULT_BADACCESS / VM_FAULT_BADMAP from
various functions, those functions should call do_fault_error()
directly, passing it VM_FAULT_SIGSEGV and the appropriate si_code.
But this is all on the s390 people to fix; I don't want to break their
arch by trying it myself.
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next prev parent reply other threads:[~2023-02-06 5:10 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-05 23:17 [PATCH 0/3] mm/arch: Fix a few collide definition on private use of VM_FAULT_* Peter Xu
2023-02-05 23:17 ` [PATCH 1/3] mm/arm: Define private VM_FAULT_* reasons from top bits Peter Xu
2023-02-05 23:17 ` [PATCH 2/3] mm/arm64: " Peter Xu
2023-02-05 23:17 ` [PATCH 3/3] mm/s390: " Peter Xu
2023-02-09 20:10 ` Heiko Carstens
2023-02-06 0:10 ` [PATCH 0/3] mm/arch: Fix a few collide definition on private use of VM_FAULT_* Matthew Wilcox
2023-02-06 0:54 ` Peter Xu
2023-02-06 2:51 ` Matthew Wilcox
2023-02-06 3:18 ` Peter Xu
2023-02-06 5:09 ` Matthew Wilcox [this message]
2023-02-09 20:04 ` Heiko Carstens
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