linux-kernel - Re: [PATCH v2 1/1] arch/fault: don't print logs for pte marker poison errors

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Message-ID: <ZkSUaVx3uCIPkpkJ@localhost.localdomain>
Date: Wed, 15 May 2024 12:54:33 +0200
From: Oscar Salvador <osalvador@...e.de>
To: Borislav Petkov <bp@...en8.de>
Cc: Axel Rasmussen <axelrasmussen@...gle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Andy Lutomirski <luto@...nel.org>,
	"Aneesh Kumar K.V" <aneesh.kumar@...nel.org>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	David Hildenbrand <david@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, Helge Deller <deller@....de>,
	Ingo Molnar <mingo@...hat.com>,
	"James E.J. Bottomley" <James.Bottomley@...senpartnership.com>,
	John Hubbard <jhubbard@...dia.com>,
	Liu Shixin <liushixin2@...wei.com>,
	"Matthew Wilcox (Oracle)" <willy@...radead.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Muchun Song <muchun.song@...ux.dev>,
	"Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
	Nicholas Piggin <npiggin@...il.com>, Peter Xu <peterx@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, linux-parisc@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org, x86@...nel.org
Subject: Re: [PATCH v2 1/1] arch/fault: don't print logs for pte marker
 poison errors

On Wed, May 15, 2024 at 12:41:42PM +0200, Borislav Petkov wrote:
> On Fri, May 10, 2024 at 11:29:26AM -0700, Axel Rasmussen wrote:
> > @@ -3938,7 +3938,7 @@ static vm_fault_t handle_pte_marker(struct vm_fault *vmf)
> >  
> >  	/* Higher priority than uffd-wp when data corrupted */
> >  	if (marker & PTE_MARKER_POISONED)
> > -		return VM_FAULT_HWPOISON;
> > +		return VM_FAULT_HWPOISON | VM_FAULT_HWPOISON_SILENT;
> 
> If you know here that this poisoning should be silent, why do you have
> to make it all complicated and propagate it into arch code, waste
> a separate VM_FAULT flag just for that instead of simply returning here
> a VM_FAULT_COMPLETED or some other innocuous value which would stop
> processing the fault?

AFAIK, He only wants it to be silent wrt. the arch fault handler not screaming,
but he still wants to be able to trigger force_sig_mceerr().


-- 
Oscar Salvador
SUSE Labs