From: Oscar Salvador <osalvador@suse.de>
To: David Hildenbrand <david@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Dave Hansen <dave.hansen@linux.intel.com>,
Andy Lutomirski <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H . Peter Anvin" <hpa@zytor.com>,
Michal Hocko <mhocko@kernel.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/2] x86/vmemmap: Handle unpopulated sub-pmd ranges
Date: Tue, 2 Feb 2021 14:52:53 +0100 [thread overview]
Message-ID: <20210202135248.GA14438@linux> (raw)
In-Reply-To: <f1990f9d-305c-f5f9-e77d-5c5d71143672@redhat.com>
On Tue, Feb 02, 2021 at 02:29:11PM +0100, David Hildenbrand wrote:
> > @@ -1088,10 +1150,10 @@ remove_pud_table(pud_t *pud_start, unsigned long addr, unsigned long end,
> > pages++;
> > } else {
> > /* If here, we are freeing vmemmap pages. */
> > - memset((void *)addr, PAGE_INUSE, next - addr);
> > + memset((void *)addr, PAGE_UNUSED, next - addr);
> > page_addr = page_address(pud_page(*pud));
> > - if (!memchr_inv(page_addr, PAGE_INUSE,
> > + if (!memchr_inv(page_addr, PAGE_UNUSED,
> > PUD_SIZE)) {
> > free_pagetable(pud_page(*pud),
> > get_order(PUD_SIZE));
>
> I'm sorry to bother you again, but isn't that dead code as well?
Heh, I spotted that earlier, but I did not think much of it honestly.
All this was introduced by:
commit ae9aae9eda2db71bf4b592f15618b0160eb07731
Author: Wen Congyang <wency@cn.fujitsu.com>
Date: Fri Feb 22 16:33:04 2013 -0800
memory-hotplug: common APIs to support page tables hot-remove
> How do we ever end up using 1GB pages for the vmemmap? At least not via
> vmemmap_populate() - so I guess never? There are not many occurrences of
> "PUD_SIZE" in the file after all ...
AFAICT, we don't. The largest we populate for vmemmap is 2MB.
I see init_memory_mapping can use 1G, but that should not affect us.
I guess that the vmemmap handling for 1GB can go as well.
I will update the patchset.
--
Oscar Salvador
SUSE L3
next prev parent reply other threads:[~2021-02-02 14:00 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-02 11:24 [PATCH 0/2] Cleanup and fixups for vmemmap handling Oscar Salvador
2021-02-02 11:24 ` [PATCH 1/2] x86/vmemmap: Remove !PAGE_ALIGNED case in remove_pte_table Oscar Salvador
2021-02-02 13:20 ` David Hildenbrand
2021-02-02 11:24 ` [PATCH 2/2] x86/vmemmap: Handle unpopulated sub-pmd ranges Oscar Salvador
2021-02-02 13:29 ` David Hildenbrand
2021-02-02 13:52 ` Oscar Salvador [this message]
2021-02-02 20:17 ` kernel test robot
2021-02-02 20:17 ` kernel test robot
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