linux-kernel - RE: [PATCH v3] x86/fault: Send a SIGBUS to user process always for hwpoison page access.

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Message-ID: <8d0c76f97f35499f91a2b82d3e7c024d@intel.com>
Date:   Mon, 1 Mar 2021 19:02:41 +0000
From:   "Luck, Tony" <tony.luck@...el.com>
To:     Andy Lutomirski <luto@...nel.org>, Aili Yao <yaoaili@...gsoft.com>
CC:     HORIGUCHI NAOYA( 堀口 直也) 
        <naoya.horiguchi@....com>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "Peter Zijlstra" <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        "Ingo Molnar" <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, X86 ML <x86@...nel.org>,
        "yangfeng1@...gsoft.com" <yangfeng1@...gsoft.com>,
        Linux-MM <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH v3] x86/fault: Send a SIGBUS to user process always for
 hwpoison page access.

> Some programs may use read(2), write(2), etc as ways to check if
> memory is valid without getting a signal.  They might not want
> signals, which means that this feature might need to be configurable.

That sounds like an appalling hack. If users need such a mechanism
we should create some better way to do that.

An aeon ago ACPI created the RASF table as a way for the OS to
ask the platform to scan a block of physical memory using the patrol
scrubber in the memory controller.  I never did anything with it in Linux
because it was just too complex and didn't know of any use cases.

Users would want to check virtual addresses. Perhaps some new
option MADV_CHECKFORPOISON to madvise(2) ?

-Tony