From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BDB0B3ACF1E for ; Sun, 2 Aug 2026 16:14:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785687246; cv=none; b=ZIzKlizJ5ZZAlgZzIk7cRuKXGz85UEin6VHOUmoKtB7bEQUKpcUF4003oTPrmq2xYPI0cYusSXMSSJ/AdeWVlqCR3GzdHEZnfvLz1zteqZD6uYqxCloqkljZ4pt4FIRpxo9wywCPwsIBX1iecpuhpQTVLa8dxzhUbjkG9L3lH+U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785687246; c=relaxed/simple; bh=RqwyKj4+nfJfmSz8/RoCF3w0WN3ag7TIMFyg7qqDl5I=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Lw19he7/4RL0jjrvtzpDp/zUWljVhmFEroQzak3qBvlCXvla2HEJlVrU7pSQR7bPnI8W0RGoo1ogHUVJlT3a/LDp37HY+PTBJLQsKPgO2JLaDvVjmmisBq++UNjev/IeqBReqEUc+GTz1HM8so7QNojtdodoAueYepls4bFm1Hk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=lhufBt+1; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="lhufBt+1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 386C91F000E9; Sun, 2 Aug 2026 16:13:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1785687244; bh=iOgh6AwBFUfLjYfZK93RPZ07a6OmymGwQZcUl0F0LPo=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=lhufBt+1XNJzEcjIqIcJ+1N2abIk1ly1qIIe43EMZFBn1onbJT+yEvwkapRDQeGPm YDtFviqqr0u03loYYqQ3lFbBsJyCTb2JQl71Jilnftn1xwZPAR1L+7DMrncNuSBIAa ZLDvpvErdwINXBNW/GavrD9Qv/Eos7oU5SbO7JOsUlZc0r+6ETUIiCznKXqO6yRCd5 S+haPKqdJjpl7ptpbg6xhxN55C7XCZDcyvm6cD47/Z++SOmxVqAbYMQSbNl+FB33w7 wBWAdhVf4W1r9YWJ66jqbZlv1u7v55M6neWNkaIALfw23TgZyp4zEcDkPcyjPWo3wl c6zW3LnrZvwOA== Date: Sun, 2 Aug 2026 19:13:55 +0300 From: Mike Rapoport To: Brendan Jackman Cc: Borislav Petkov , Dave Hansen , Peter Zijlstra , Andrew Morton , David Hildenbrand , Vlastimil Babka , Wei Xu , Johannes Weiner , Zi Yan , Lorenzo Stoakes , linux-mm@kvack.org, linux-kernel@vger.kernel.org, x86@kernel.org, Sumit Garg , Will Deacon , rientjes@google.com, "Kalyazin, Nikita" , patrick.roy@linux.dev, "Itazuri, Takahiro" , Andy Lutomirski , David Kaplan , Thomas Gleixner , Yosry Ahmed , Patrick Bellasi , Reiji Watanabe , Sean Christopherson Subject: Re: [PATCH v3 04/26] x86/mm: split out preallocate_sub_pgd() Message-ID: References: <20260726-page_alloc-unmapped-v3-0-6f5729aa9832@google.com> <20260726-page_alloc-unmapped-v3-4-6f5729aa9832@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260726-page_alloc-unmapped-v3-4-6f5729aa9832@google.com> On Sun, Jul 26, 2026 at 10:22:37PM +0000, Brendan Jackman wrote: > This code will be needed elsewhere in a following patch. Split out the > trivial code move for easy review. > > As a side effect, change the logging slightly: instead of directly > reporting the level of the failure in panic(), show a generic panic > message, will be preceded by a separate warn that reports the level of > the failure. This is a simple way to have this helper suit the needs of > its new user as well as the existing one. > > Other than logging, no functional change intended. > > Signed-off-by: Brendan Jackman > --- > arch/x86/include/asm/pgalloc.h | 3 +++ > arch/x86/mm/init_64.c | 44 +++++++----------------------------------- > arch/x86/mm/pgtable.c | 38 ++++++++++++++++++++++++++++++++++++ > 3 files changed, 48 insertions(+), 37 deletions(-) > > diff --git a/arch/x86/include/asm/pgalloc.h b/arch/x86/include/asm/pgalloc.h > index c88691b15f3c6..2aba6cfabf495 100644 > --- a/arch/x86/include/asm/pgalloc.h > +++ b/arch/x86/include/asm/pgalloc.h > @@ -2,6 +2,7 @@ > #ifndef _ASM_X86_PGALLOC_H > #define _ASM_X86_PGALLOC_H > > +#include I think this should go to arch/x86/mm/pgtable.c. pgalloc.h does not need printk symbols. > #include > #include /* for struct page */ > #include > @@ -128,6 +129,8 @@ static inline void __pud_free_tlb(struct mmu_gather *tlb, pud_t *pud, > ___pud_free_tlb(tlb, pud); > } > > +extern int preallocate_sub_pgd(struct mm_struct *mm, unsigned long addr); > + > #if CONFIG_PGTABLE_LEVELS > 4 > static inline void pgd_populate(struct mm_struct *mm, pgd_t *pgd, p4d_t *p4d) > { > diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c > index ab4c5a02326f7..ac6688c70872e 100644 > --- a/arch/x86/mm/init_64.c > +++ b/arch/x86/mm/init_64.c > @@ -1293,46 +1293,16 @@ static struct kcore_list kcore_vsyscall; > static void __init preallocate_vmalloc_pages(void) > { > unsigned long addr; > - const char *lvl; > > for (addr = VMALLOC_START; addr <= VMEMORY_END; addr = ALIGN(addr + 1, PGDIR_SIZE)) { > - pgd_t *pgd = pgd_offset_k(addr); > - p4d_t *p4d; > - pud_t *pud; > - > - lvl = "p4d"; > - p4d = p4d_alloc(&init_mm, pgd, addr); > - if (!p4d) > - goto failed; > - > - if (pgtable_l5_enabled()) > - continue; > - > - /* > - * The goal here is to allocate all possibly required > - * hardware page tables pointed to by the top hardware > - * level. > - * > - * On 4-level systems, the P4D layer is folded away and > - * the above code does no preallocation. Below, go down > - * to the pud _software_ level to ensure the second > - * hardware level is allocated on 4-level systems too. > - */ > - lvl = "pud"; > - pud = pud_alloc(&init_mm, p4d, addr); > - if (!pud) > - goto failed; > + if (preallocate_sub_pgd(&init_mm, addr)) { > + /* > + * The pages have to be there now or they will be > + * missing in process page-tables later. > + */ > + panic("Failed to pre-allocate pagetables for vmalloc area\n"); > + } > } > - > - return; > - > -failed: > - > - /* > - * The pages have to be there now or they will be missing in > - * process page-tables later. > - */ > - panic("Failed to pre-allocate %s pages for vmalloc area\n", lvl); > } > > void __init arch_mm_preinit(void) > diff --git a/arch/x86/mm/pgtable.c b/ > index f32facdb30354..fdd3709509946 100644 > --- a/arch/x86/mm/pgtable.c > +++ b/arch/x86/mm/pgtable.c > @@ -833,3 +833,41 @@ void arch_check_zapped_pud(struct vm_area_struct *vma, pud_t pud) > /* See note in arch_check_zapped_pte() */ > VM_WARN_ON_ONCE(!(vma->vm_flags & VM_SHADOW_STACK) && pud_shstk(pud)); > } > + > +#if CONFIG_PGTABLE_LEVELS > 3 > +/* > + * Allocate all possibly required hardware page tables pointed to ths > + * top hardware level. In other words, allocate a p4d on 5-level or a > + * pud on 4-level. > + */ > +int preallocate_sub_pgd(struct mm_struct *mm, unsigned long addr) > +{ > + const char *lvl; > + p4d_t *p4d; > + pud_t *pud; > + > + lvl = "p4d"; > + p4d = p4d_alloc(mm, pgd_offset_pgd(mm->pgd, addr), addr); > + if (!p4d) > + goto failed; > + > + if (pgtable_l5_enabled()) > + return 0; > + > + /* > + * On 4-level systems, the P4D layer is folded away and > + * the above code does no preallocation. Below, go down > + * to the pud _software_ level to ensure the second > + * hardware level is allocated on 4-level systems too. > + */ > + lvl = "pud"; > + pud = pud_alloc(mm, p4d, addr); > + if (!pud) > + goto failed; > + return 0; > + > +failed: > + pr_warn_ratelimited("Failed to preallocate %s\n", lvl); > + return -ENOMEM; > +} > +#endif > > -- > 2.54.0 > -- Sincerely yours, Mike.