From: Pavel Tatashin <pasha.tatashin@oracle.com>
To: hejianet@gmail.com
Cc: linux@armlinux.org.uk, Andrew Morton <akpm@linux-foundation.org>,
Michal Hocko <mhocko@suse.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Mel Gorman <mgorman@suse.de>,
will.deacon@arm.com, mark.rutland@arm.com, hpa@zytor.com,
Daniel Jordan <daniel.m.jordan@oracle.com>,
AKASHI Takahiro <takahiro.akashi@linaro.org>,
Gioh Kim <gi-oh.kim@profitbricks.com>,
Steven Sistare <steven.sistare@oracle.com>,
neelx@redhat.com, erosca@de.adit-jv.com,
Vlastimil Babka <vbabka@suse.cz>,
LKML <linux-kernel@vger.kernel.org>,
Linux Memory Management List <linux-mm@kvack.org>,
james.morse@arm.com, ard.biesheuvel@linaro.org,
steve.capper@arm.com, tglx@linutronix.de, mingo@redhat.com,
gregkh@linuxfoundation.org, kstewart@linuxfoundation.org,
pombredanne@nexb.com, Johannes Weiner <hannes@cmpxchg.org>,
kemi.wang@intel.com, ptesarik@suse.com, yasu.isimatu@gmail.com,
aryabinin@virtuozzo.com, nborisov@suse.com,
Wei Yang <richard.weiyang@gmail.com>,
jia.he@hxt-semitech.com
Subject: Re: [PATCH v9 2/6] mm: page_alloc: remain memblock_next_valid_pfn() on arm/arm64
Date: Fri, 29 Jun 2018 13:07:02 -0400 [thread overview]
Message-ID: <CAGM2reZ3zYdrYBEGTdy+LLm_HPREyqYeUqqQnU1GCPd3k98z3Q@mail.gmail.com> (raw)
In-Reply-To: <1530239363-2356-3-git-send-email-hejianet@gmail.com>
On Thu, Jun 28, 2018 at 10:30 PM Jia He <hejianet@gmail.com> wrote:
>
> Commit b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns
> where possible") optimized the loop in memmap_init_zone(). But it causes
> possible panic bug. So Daniel Vacek reverted it later.
>
> But as suggested by Daniel Vacek, it is fine to using memblock to skip
> gaps and finding next valid frame with CONFIG_HAVE_ARCH_PFN_VALID.
>
> On arm and arm64, memblock is used by default. But generic version of
> pfn_valid() is based on mem sections and memblock_next_valid_pfn() does
> not always return the next valid one but skips more resulting in some
> valid frames to be skipped (as if they were invalid). And that's why
> kernel was eventually crashing on some !arm machines.
Hi Jia,
Is this a bug? Should we make other arches that support memblock to
use memblock_is_map_memory() ? it is more expensive, but if the
default is broken, maybe it makes sense to change?
Thank you,
Pavel
next prev parent reply other threads:[~2018-06-29 17:07 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-06-29 2:29 [PATCH v9 0/6] optimize memblock_next_valid_pfn and early_pfn_valid on arm and arm64 Jia He
2018-06-29 2:29 ` [PATCH v9 1/6] arm: arm64: introduce CONFIG_HAVE_MEMBLOCK_PFN_VALID Jia He
2018-06-29 18:08 ` Pavel Tatashin
2018-06-29 2:29 ` [PATCH v9 2/6] mm: page_alloc: remain memblock_next_valid_pfn() on arm/arm64 Jia He
2018-06-29 17:07 ` Pavel Tatashin [this message]
2018-07-06 1:38 ` Jia He
2018-06-29 18:13 ` Pavel Tatashin
2018-07-02 11:38 ` Michal Hocko
2018-07-03 1:55 ` Jia He
2018-07-03 3:03 ` Pavel Tatashin
2018-06-29 2:29 ` [PATCH v9 3/6] arm: arm64: page_alloc: reduce unnecessary binary search in memblock_next_valid_pfn() Jia He
2018-06-29 2:29 ` [PATCH v9 4/6] mm/memblock: introduce memblock_search_pfn_regions() Jia He
2018-06-29 2:29 ` [PATCH v9 5/6] arm: arm64: introduce pfn_valid_region() Jia He
2018-06-29 2:29 ` [PATCH v9 6/6] mm: page_alloc: reduce unnecessary binary search in early_pfn_valid() Jia He
2018-07-02 11:40 ` [PATCH v9 0/6] optimize memblock_next_valid_pfn and early_pfn_valid on arm and arm64 Michal Hocko
2018-07-02 12:06 ` Pavel Tatashin
2018-07-03 2:00 ` Jia He
2018-07-03 2:11 ` Jia He
2018-07-03 7:28 ` Michal Hocko
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