From mboxrd@z Thu Jan  1 00:00:00 1970
From: Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH v3 20/23] fs: Allow copy_mount_options() to access
 user-space in a single pass
Date: Tue, 21 Apr 2020 16:29:48 +0100
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References: <20200421142603.3894-1-catalin.marinas@arm.com>
 <20200421142603.3894-21-catalin.marinas@arm.com>
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To: Catalin Marinas <catalin.marinas@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, Will Deacon <will@kernel.org>, Vincenzo Frascino <vincenzo.frascino@arm.com>, Szabolcs Nagy <szabolcs.nagy@arm.com>, Richard Earnshaw <Richard.Earnshaw@arm.com>, Kevin Brodsky <kevin.brodsky@arm.com>, Andrey Konovalov <andreyknvl@google.com>, Peter Collingbourne <pcc@google.com>, linux-mm@kvack.org, linux-arch@vger.kernel.org

On Tue, Apr 21, 2020 at 03:26:00PM +0100, Catalin Marinas wrote:

> While this function is not on a critical path, the single-pass behaviour
> is required for arm64 MTE (memory tagging) support where a uaccess can
> trigger intra-page faults (tag not matching). With the current
> implementation, if this happens during the first page, the function will
> return -EFAULT.

Details, please.

From mboxrd@z Thu Jan  1 00:00:00 1970
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Date: Tue, 21 Apr 2020 16:29:48 +0100
From: Al Viro <viro@zeniv.linux.org.uk>
Subject: Re: [PATCH v3 20/23] fs: Allow copy_mount_options() to access
 user-space in a single pass
Message-ID: <20200421152948.GC23230@ZenIV.linux.org.uk>
References: <20200421142603.3894-1-catalin.marinas@arm.com>
 <20200421142603.3894-21-catalin.marinas@arm.com>
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To: Catalin Marinas <catalin.marinas@arm.com>
Cc: linux-arm-kernel@lists.infradead.org, Will Deacon <will@kernel.org>, Vincenzo Frascino <vincenzo.frascino@arm.com>, Szabolcs Nagy <szabolcs.nagy@arm.com>, Richard Earnshaw <Richard.Earnshaw@arm.com>, Kevin Brodsky <kevin.brodsky@arm.com>, Andrey Konovalov <andreyknvl@google.com>, Peter Collingbourne <pcc@google.com>, linux-mm@kvack.org, linux-arch@vger.kernel.org
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On Tue, Apr 21, 2020 at 03:26:00PM +0100, Catalin Marinas wrote:

> While this function is not on a critical path, the single-pass behaviour
> is required for arm64 MTE (memory tagging) support where a uaccess can
> trigger intra-page faults (tag not matching). With the current
> implementation, if this happens during the first page, the function will
> return -EFAULT.

Details, please.