From: David Miller <davem@davemloft.net>
To: chris@chris-wilson.co.uk
Cc: linux@roeck-us.net, linux-kernel@vger.kernel.org,
akpm@linux-foundation.org, sparclinux@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: Crash in -next due to 'mm/vmalloc: replace opencoded 4-level page walkers'
Date: Mon, 09 Jan 2017 14:48:59 -0500 (EST) [thread overview]
Message-ID: <20170109.144859.1717139396935735509.davem@davemloft.net> (raw)
In-Reply-To: <20170109113707.GQ19067@nuc-i3427.alporthouse.com>
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Mon, 9 Jan 2017 11:37:07 +0000
> Could some mm expert explain why it is safe for mm/vmalloc.c to ignore
> huge pud/pmd that raise BUG_ON in the same code in mm/memory.c
> (vmap_pmd_range() vs apply_to_pmd_range())?
>
> At a guess, is sparc64 covering the init_mm with a huge zero page? How
> is it then meant to be split? Something like
We map the linear physical area (PAGE_OFFSET --> PAGE_OFFSET +
max_phys_addr) using huge pages unless DEBUG_PAGEALLOC is enabled.
It is not meant to be split, and that's why we don't use huge pages
when DEBUG_PAGEALLOC is set since that requires changes to the mapping
to be possible.
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prev parent reply other threads:[~2017-01-09 19:49 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20161028171825.GA15116@roeck-us.net>
2016-10-28 20:15 ` Chris Wilson
2016-10-28 21:26 ` Andrew Morton
2017-01-09 11:37 ` Chris Wilson
2017-01-09 19:48 ` David Miller [this message]
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