From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 711353ED111 for ; Mon, 16 Mar 2026 19:56:31 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773690991; cv=none; b=XRA2Bz1fwe5OhduqpyqQEZy4ws9S4iPmRAu8XR7A72SFTS8MfOzsPRJ4i7LBeL06DR4AUGEnslLI1rmA8F4VTZYJjVg5gME/cIFWEoht70MPCR6MUKBDXiEEcwsnzU3oam2H0fo0tpqwRubgrMbNnABXgbF8UXouwpMMVf6WeDk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773690991; c=relaxed/simple; bh=60efY1x/+67vV2eprX/IU6yUD/7n5IHV27Dsmf39qYw=; h=Date:To:From:Subject:Message-Id; b=Ysy7Lm5wVwvR0+rjIvmNoTxxR6fXyGz4W9N4SAmrUx6qHfIvTGNfL4+up9jw87T43OEa4HjgCU7BJcP6cntWjvRQk0mpwJ1tJ5jp4KXp48IOfme3lOFd5XhvJTwi2z7eLYNWw1vPJk8kDSCsaswmUWuIASsMEDiKbWsVrCQiDMQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=galYK9Zv; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="galYK9Zv" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C9C35C2BC9E; Mon, 16 Mar 2026 19:56:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1773690990; bh=60efY1x/+67vV2eprX/IU6yUD/7n5IHV27Dsmf39qYw=; h=Date:To:From:Subject:From; b=galYK9ZvJyGQYaGJ8Lcosp6BvYzb6nb9RWz9puTSgK1rndPAC/oQr51CB8GUnqbJE LbBpHv5CMtqBEDQkOh9XOHEzggMrIS8qm/yX0XLaLFMVJ+tnHQBicnvc3IjmPuHnQe DxpBEaclZIDU8giDXP5FiR55DtqFepNLaR2zre0A= Date: Mon, 16 Mar 2026 12:56:30 -0700 To: mm-commits@vger.kernel.org,muchun.song@linux.dev,david@kernel.org,kas@kernel.org,akpm@linux-foundation.org From: Andrew Morton Subject: + hugetlb-update-vmemmap_deduprst-fix.patch added to mm-unstable branch Message-Id: <20260316195630.C9C35C2BC9E@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: hugetlb: update vmemmap_dedup.rst has been added to the -mm mm-unstable branch. Its filename is hugetlb-update-vmemmap_deduprst-fix.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/hugetlb-update-vmemmap_deduprst-fix.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via various branches at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there most days ------------------------------------------------------ From: Kiryl Shutsemau Subject: hugetlb: update vmemmap_dedup.rst Date: Mon, 2 Mar 2026 10:56:28 +0000 Update the documentation regarding vmemmap optimization for hugetlb to reflect the changes in how the kernel maps the tail pages. Fake heads no longer exist. Remove their description. Link: https://lkml.kernel.org/r/20260302105630.303492-1-kas@kernel.org Signed-off-by: Kiryl Shutsemau Reviewed-by: Muchun Song Reviewed-by: David Hildenbrand (Arm) Signed-off-by: Andrew Morton --- Documentation/mm/vmemmap_dedup.rst | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/Documentation/mm/vmemmap_dedup.rst~hugetlb-update-vmemmap_deduprst-fix +++ a/Documentation/mm/vmemmap_dedup.rst @@ -128,8 +128,8 @@ The first page of ``struct page`` (page contains the 4 ``struct page`` necessary to describe the HugeTLB. The remaining pages of ``struct page`` (page 1 to page 7) are tail pages. -The optimization is only applied when the size of the struct page is a power-of-2 -In this case, all tail pages of the same order are identical. See +The optimization is only applied when the size of the struct page is a power +of 2. In this case, all tail pages of the same order are identical. See compound_head(). This allows us to remap the tail pages of the vmemmap to a shared, read-only page. The head page is also remapped to a new page. This allows the original vmemmap pages to be freed. @@ -143,7 +143,7 @@ Here is how things look after remapping: | | | 1 | ------┐ | | +-----------+ | | | | 2 | ------┼ +----------------------------+ - | | +-----------+ | | A single, per-node page | + | | +-----------+ | | A single, per-zone page | | | | 3 | ------┼------> | frame shared among all | | | +-----------+ | | hugepages of the same size | | | | 4 | ------┼ +----------------------------+ _ Patches currently in -mm which might be from kas@kernel.org are mm-move-max_folio_order-definition-to-mmzoneh.patch mm-change-the-interface-of-prep_compound_tail.patch mm-rename-the-compound_head-field-in-the-struct-page-to-compound_info.patch mm-move-set-clear_compound_head-next-to-compound_head.patch riscv-mm-align-vmemmap-to-maximal-folio-size.patch loongarch-mm-align-vmemmap-to-maximal-folio-size.patch mm-rework-compound_head-for-power-of-2-sizeofstruct-page.patch mm-sparse-check-memmap-alignment-for-compound_info_has_mask.patch mm-hugetlb-defer-vmemmap-population-for-bootmem-hugepages.patch mm-hugetlb-refactor-code-around-vmemmap_walk.patch x86-vdso-undefine-config_hugetlb_page_optimize_vmemmap-for-vdso32.patch mm-hugetlb-remove-fake-head-pages.patch mm-drop-fake-head-checks.patch hugetlb-remove-vmemmap_synchronize_rcu.patch mm-hugetlb-remove-hugetlb_optimize_vmemmap_key-static-key.patch mm-remove-the-branch-from-compound_head.patch hugetlb-update-vmemmap_deduprst.patch hugetlb-update-vmemmap_deduprst-fix.patch mm-slab-use-compound_head-in-page_slab.patch