From: Anshuman Khandual <anshuman.khandual@arm.com>
To: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, akpm@linux-foundation.org,
catalin.marinas@arm.com, will.deacon@arm.com
Cc: mark.rutland@arm.com, mhocko@suse.com, david@redhat.com,
ira.weiny@intel.com, steve.capper@arm.com,
mgorman@techsingularity.net, cai@lca.pw, ard.biesheuvel@arm.com,
cpandya@codeaurora.org, james.morse@arm.com,
dan.j.williams@intel.com, logang@deltatee.com,
arunks@codeaurora.org, osalvador@suse.de
Subject: Re: [PATCH V6 3/3] arm64/mm: Enable memory hot remove
Date: Fri, 21 Jun 2019 18:23:22 +0530 [thread overview]
Message-ID: <bc46b390-01b8-e818-588d-f973dc2c5140@arm.com> (raw)
In-Reply-To: <1560917860-26169-4-git-send-email-anshuman.khandual@arm.com>
On 06/19/2019 09:47 AM, Anshuman Khandual wrote:
> +#ifdef CONFIG_MEMORY_HOTPLUG
> + /*
> + * FIXME: We should have called remove_pagetable(start, end, true).
> + * vmemmap and vmalloc virtual range might share intermediate kernel
> + * page table entries. Removing vmemmap range page table pages here
> + * can potentially conflict with a cuncurrent vmalloc() allocation.
> + *
> + * This is primarily because valloc() does not take init_mm ptl for
> + * the entire page table walk and it's modification. Instead it just
> + * takes the lock while allocating and installing page table pages
> + * via [p4d|pud|pmd|pte]_aloc(). A cuncurrently vanishing page table
> + * entry via memory hotremove can cause vmalloc() kernel page table
> + * walk pointers to be invalid on the fly which can cause corruption
> + * or worst, a crash.
There are couple of typos above which I will fix along with other reviews.
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next prev parent reply other threads:[~2019-06-21 12:53 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-19 4:17 [PATCH V6 0/3] arm64/mm: Enable memory hot remove Anshuman Khandual
2019-06-19 4:17 ` [PATCH V6 1/3] mm/hotplug: Reorder memblock_[free|remove]() calls in try_remove_memory() Anshuman Khandual
2019-06-19 4:17 ` [PATCH V6 2/3] arm64/mm: Hold memory hotplug lock while walking for kernel page table dump Anshuman Khandual
2019-06-19 4:17 ` [PATCH V6 3/3] arm64/mm: Enable memory hot remove Anshuman Khandual
2019-06-21 12:53 ` Anshuman Khandual [this message]
2019-06-21 14:35 ` Steve Capper
2019-06-24 3:12 ` Anshuman Khandual
2019-06-24 16:52 ` Mark Rutland
2019-06-25 5:27 ` Anshuman Khandual
2019-06-25 10:31 ` Mark Rutland
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