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Peter Anvin" , Michal Hocko , linux-mm@kvack.org, linux-kernel@vger.kernel.org References: <20210203104750.23405-1-osalvador@suse.de> <20210203104750.23405-3-osalvador@suse.de> From: David Hildenbrand Organization: Red Hat GmbH Message-ID: Date: Wed, 3 Feb 2021 14:33:56 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.5.0 MIME-Version: 1.0 In-Reply-To: <20210203104750.23405-3-osalvador@suse.de> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 03.02.21 11:47, Oscar Salvador wrote: > We never get to allocate 1GB pages when mapping the vmemmap range. > Drop the dead code both for the aligned and unaligned cases and leave > only the direct map handling. > > Signed-off-by: Oscar Salvador > Suggested-by: David Hildenbrand > --- > arch/x86/mm/init_64.c | 31 ++++--------------------------- > 1 file changed, 4 insertions(+), 27 deletions(-) > > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c > index b0e1d215c83e..28729c6b9775 100644 > --- a/arch/x86/mm/init_64.c > +++ b/arch/x86/mm/init_64.c > @@ -1062,7 +1062,6 @@ remove_pud_table(pud_t *pud_start, unsigned long addr, unsigned long end, > unsigned long next, pages = 0; > pmd_t *pmd_base; > pud_t *pud; > - void *page_addr; > > pud = pud_start + pud_index(addr); > for (; addr < end; addr = next, pud++) { > @@ -1072,32 +1071,10 @@ remove_pud_table(pud_t *pud_start, unsigned long addr, unsigned long end, > continue; > > if (pud_large(*pud)) { > - if (IS_ALIGNED(addr, PUD_SIZE) && > - IS_ALIGNED(next, PUD_SIZE)) { > - if (!direct) > - free_pagetable(pud_page(*pud), > - get_order(PUD_SIZE)); > - > - spin_lock(&init_mm.page_table_lock); > - pud_clear(pud); > - spin_unlock(&init_mm.page_table_lock); > - pages++; > - } else { > - /* If here, we are freeing vmemmap pages. */ > - memset((void *)addr, PAGE_INUSE, next - addr); > - > - page_addr = page_address(pud_page(*pud)); > - if (!memchr_inv(page_addr, PAGE_INUSE, > - PUD_SIZE)) { > - free_pagetable(pud_page(*pud), > - get_order(PUD_SIZE)); > - > - spin_lock(&init_mm.page_table_lock); > - pud_clear(pud); > - spin_unlock(&init_mm.page_table_lock); > - } > - } > - > + spin_lock(&init_mm.page_table_lock); > + pud_clear(pud); > + spin_unlock(&init_mm.page_table_lock); > + pages++; > continue; > } One problem I see with existing code / this change making more obvious is that when trying to remove in other granularity than we added (e.g., unplug a 128MB DIMM avaialble during boot), we remove the direct map of unrelated DIMMs. I think we should keep the if (IS_ALIGNED(addr, PUD_SIZE) && IS_ALIGNED(next, PUD_SIZE)) { ... } bits. Thoguhts? Apart from that looks good. -- Thanks, David / dhildenb