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 54C4513D897 for ; Sat, 12 Oct 2024 22:22:03 +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=1728771724; cv=none; b=Gz+vMdiZWW9YWL8p52srMOU8HcRZxkxqk5DZd4fD1OksayeK6XD2O+fAbSgO+zttiVvUt9OR5aTUd6rBclBImA+jZWPnOCeKz1+BEZEKztYPjNvq75XmM1VQ4mh5/rSD/qLBtfJTALYBQw1WjWGSaKSZGWvHGsJ7J1iG6dTkAnA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1728771724; c=relaxed/simple; bh=fjilsVe1a80tPGSkZ0rRLQBzDDXbagw4rDtkt3pi2j4=; h=Date:To:From:Subject:Message-Id; b=E2AvW6sSOxh96i0U7bZOAv7oFztrI1DCpcd04HKvNNsHcOEw1obd8MjRDVaUMqYBIYxKk1MYnvtPe5z3GDAeOWQt83azuC5oaQMhm5F7GdQ+Up+zIqvE9xpbsK2/f8kgljYutc6cqkRMjPA6hDJ/nLi7rcEmUGVx7UAMJ9OJIRs= 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=EDvZocM2; 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="EDvZocM2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id C2DF8C4CEC6; Sat, 12 Oct 2024 22:22:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1728771723; bh=fjilsVe1a80tPGSkZ0rRLQBzDDXbagw4rDtkt3pi2j4=; h=Date:To:From:Subject:From; b=EDvZocM2kMn55kW7s3tf75SGqOw57rqOPcaDd7n/t6HRaDJfXjNN3C4Qmt9DC5eg8 XEH1WNaLntw3Q03DSaFIKGHgAcfgTrC/Ca9EUOdr3PxaADzXjhyr1uBBeYeOYeqi2I fkUb45Mdiy2Tz1IJFm6YEKVaGFkXKoIV6dt4MXO8= Date: Sat, 12 Oct 2024 15:22:03 -0700 To: mm-commits@vger.kernel.org,ying.huang@intel.com,willy@infradead.org,wangkefeng.wang@huawei.com,ryan.roberts@arm.com,linmiaohe@huawei.com,keescook@chromium.org,jhubbard@nvidia.com,glider@google.com,david@redhat.com,ziy@nvidia.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-avoid-zeroing-user-movable-page-twice-with-init_on_alloc=1.patch added to mm-unstable branch Message-Id: <20241012222203.C2DF8C4CEC6@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm: avoid zeroing user movable page twice with init_on_alloc=1 has been added to the -mm mm-unstable branch. Its filename is mm-avoid-zeroing-user-movable-page-twice-with-init_on_alloc=1.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-avoid-zeroing-user-movable-page-twice-with-init_on_alloc=1.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 the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Zi Yan Subject: mm: avoid zeroing user movable page twice with init_on_alloc=1 Date: Fri, 11 Oct 2024 11:03:04 -0400 Commit 6471384af2a6 ("mm: security: introduce init_on_alloc=1 and init_on_free=1 boot options") forces allocated page to be zeroed in post_alloc_hook() when init_on_alloc=1. For order-0 folios, if arch does not define vma_alloc_zeroed_movable_folio(), the default implementation again zeros the page return from the buddy allocator. So the page is zeroed twice. Fix it by passing __GFP_ZERO instead to avoid double page zeroing. At the moment, s390,arm64,x86,alpha,m68k are not impacted since they define their own vma_alloc_zeroed_movable_folio(). For >0 order folios (mTHP and PMD THP), folio_zero_user() is called to zero the folio again. Fix it by calling folio_zero_user() only if init_on_alloc is set. All arch are impacted. Add alloc_zeroed() helper to encapsulate the init_on_alloc check. Link: https://lkml.kernel.org/r/20241011150304.709590-1-ziy@nvidia.com Signed-off-by: Zi Yan Cc: Alexander Potapenko Cc: David Hildenbrand Cc: "Huang, Ying" Cc: John Hubbard Cc: Kees Cook Cc: Kefeng Wang Cc: Matthew Wilcox Cc: Miaohe Lin Cc: Ryan Roberts Signed-off-by: Andrew Morton --- include/linux/highmem.h | 8 +------- mm/huge_memory.c | 3 ++- mm/internal.h | 6 ++++++ mm/memory.c | 3 ++- 4 files changed, 11 insertions(+), 9 deletions(-) --- a/include/linux/highmem.h~mm-avoid-zeroing-user-movable-page-twice-with-init_on_alloc=1 +++ a/include/linux/highmem.h @@ -224,13 +224,7 @@ static inline struct folio *vma_alloc_zeroed_movable_folio(struct vm_area_struct *vma, unsigned long vaddr) { - struct folio *folio; - - folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, vaddr); - if (folio) - clear_user_highpage(&folio->page, vaddr); - - return folio; + return vma_alloc_folio(GFP_HIGHUSER_MOVABLE | __GFP_ZERO, 0, vma, vaddr); } #endif --- a/mm/huge_memory.c~mm-avoid-zeroing-user-movable-page-twice-with-init_on_alloc=1 +++ a/mm/huge_memory.c @@ -1176,7 +1176,8 @@ static struct folio *vma_alloc_anon_foli } folio_throttle_swaprate(folio, gfp); - folio_zero_user(folio, addr); + if (!alloc_zeroed()) + folio_zero_user(folio, addr); /* * The memory barrier inside __folio_mark_uptodate makes sure that * folio_zero_user writes become visible before the set_pmd_at() --- a/mm/internal.h~mm-avoid-zeroing-user-movable-page-twice-with-init_on_alloc=1 +++ a/mm/internal.h @@ -1233,6 +1233,12 @@ void touch_pud(struct vm_area_struct *vm void touch_pmd(struct vm_area_struct *vma, unsigned long addr, pmd_t *pmd, bool write); +static inline bool alloc_zeroed(void) +{ + return static_branch_maybe(CONFIG_INIT_ON_ALLOC_DEFAULT_ON, + &init_on_alloc); +} + enum { /* mark page accessed */ FOLL_TOUCH = 1 << 16, --- a/mm/memory.c~mm-avoid-zeroing-user-movable-page-twice-with-init_on_alloc=1 +++ a/mm/memory.c @@ -4719,7 +4719,8 @@ static struct folio *alloc_anon_folio(st goto next; } folio_throttle_swaprate(folio, gfp); - folio_zero_user(folio, vmf->address); + if (!alloc_zeroed()) + folio_zero_user(folio, vmf->address); return folio; } next: _ Patches currently in -mm which might be from ziy@nvidia.com are mm-avoid-zeroing-user-movable-page-twice-with-init_on_alloc=1.patch