linux-kernel - Re: why do we need vmalloc_sync

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Message-ID: <87bnghit74.fsf@tassilo.jf.intel.com>
Date:	Sun, 14 Jun 2015 19:47:11 -0700
From:	Andi Kleen <andi@...stfloor.org>
To:	Oleg Nesterov <oleg@...hat.com>
Cc:	Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, Andy Lutomirski <luto@...capital.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Denys Vlasenko <dvlasenk@...hat.com>,
	Brian Gerst <brgerst@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Borislav Petkov <bp@...en8.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Waiman Long <Waiman.Long@...com>
Subject: Re: why do we need vmalloc_sync_all?

Oleg Nesterov <oleg@...hat.com> writes:
>
> But again, the kernel no longer does this? do_page_fault() does vmalloc_fault()
> without notify_die(). If it fails, I do not see how/why a modular DIE_OOPS
> handler could try to resolve this problem and trigger another fault.

The same problem can happen from NMI handlers or machine check
handlers. It's not necessarily tied to page faults only.

-Andi

-- 
ak@...ux.intel.com -- Speaking for myself only
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