From: Oscar Salvador <osalvador@suse.de>
To: David Hildenbrand <david@redhat.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>,
Markus Gothe <markus.gothe@genexis.eu>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
Zi Yan <ziy@nvidia.com>
Subject: Re: get_pageblock_bitmap() sometimes returns a NULL pointer which needs to be properly handled
Date: Mon, 6 May 2024 12:42:56 +0200 [thread overview]
Message-ID: <Zji0MJ3fMN5AfbTb@localhost.localdomain> (raw)
In-Reply-To: <96439935-ce2a-4714-be5d-cdeb8ea0eb41@redhat.com>
On Mon, May 06, 2024 at 11:54:49AM +0200, David Hildenbrand wrote:
> But, could it be that we failing during compaction_alloc() [lr :
> compaction_alloc+0x220/0x804] and have an issue during
> set_pfnblock_flags_mask() on a page that sits on the isolated freelist?
> Similarly, memory hotunplug should not be able to mess up here.
But pageblock_flags is something that gets initialized at boot time and
never touched again (for already present sections).
There are two paths to get it:
section_to_usemap(__pfn_to_section(pfn))
or
page_zone(page)->pageblock_flags
Assuming the we somehow fail in compaction_alloc() and get a bad page or
NULL, we should crash before reaching to the point where we ask for
pageblock_flags.
--
Oscar Salvador
SUSE Labs
prev parent reply other threads:[~2024-05-06 10:43 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-02 16:02 Markus Gothe
2024-05-06 9:39 ` Baolin Wang
2024-05-06 9:51 ` Markus Gothe
2024-05-06 9:54 ` David Hildenbrand
2024-05-06 10:01 ` Markus Gothe
2024-05-06 10:45 ` David Hildenbrand
2024-05-06 10:42 ` Oscar Salvador [this message]
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