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Date: Sat, 4 Jul 2026 01:39:04 +0100
From: Matthew Wilcox <willy@infradead.org>
To: Leon Hwang <leon.hwang@linux.dev>
Cc: linux-mm@kvack.org, Jonathan Corbet <corbet@lwn.net>,
	Shuah Khan <skhan@linuxfoundation.org>,
	Andrew Morton <akpm@linux-foundation.org>,
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	linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org
Subject: Re: [PATCH] mm/mseal: fix mseal documentation for 32-bit kernels
Message-ID: <akhWKJSZLfDusVcL@casper.infradead.org>
References: <20260703022507.187457-1-leon.hwang@linux.dev>
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In-Reply-To: <20260703022507.187457-1-leon.hwang@linux.dev>

On Fri, Jul 03, 2026 at 10:25:07AM +0800, Leon Hwang wrote:
> Document the -EINTR return from mmap_write_lock_killable(), fix the

No, you don't understand the whole concept of "killable".  If a
task receives a fatal signal, it dies before it returns to userspace.
So userspace never gets to see the -EINTR.  It's fine to document inside
the kernel that function foo() can return -EINTR, but it's pointless to
document it for userspace.

This is how "killable" differs from "interruptible".  Interruptible allows
non-fatal signals to wake a task, and then the task can see the -EINTR.
But many processes do not check the error code, and so read() and write()
(despite being documented as being able to return EINTR!)  do not do so
in practise.