From patchwork Thu Jan 25 16:42:52 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexandru Elisei X-Patchwork-Id: 13531384 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 9D763144632; Thu, 25 Jan 2024 16:45:46 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706201148; cv=none; b=hnL756+VxG9XYmA5huV23M8WWFbfX0zlb34lglQusTkbtHS4bONF/Z9NxaETHWsJ1PlneKYPpNKqIhqHLgeCGs3/qRmg/wD5Z7qiZXrzWl32vQy0TDUjll1eK9BFj8uIH3gfzgze1ndb3z/kP1B/Zxy/9xKMBETUgezmmGapeEY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706201148; c=relaxed/simple; bh=MOpgrrJcQ/MuxDeBbUcSDCqPbGVfpCoyzo9ytzas7Ec=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=taTv8gPE3SR6hSvMt5Vbd/wNreLu7aQeXXinPVBFzeXC88YaRA34YG0byTKshDl0vk/b/XWzLj8fi70qdjHWqyRSC5awidSvFcb1i77g7rXWzgaGgIcIknfh4/sQwiEF9oEKQ/V628HxU7wqcPIibMy6082Z/OZ/DkcXLkqzC8A= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8549C1756; Thu, 25 Jan 2024 08:46:30 -0800 (PST) Received: from e121798.cable.virginm.net (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 945353F8A4; Thu, 25 Jan 2024 08:45:40 -0800 (PST) From: Alexandru Elisei To: catalin.marinas@arm.com, will@kernel.org, oliver.upton@linux.dev, maz@kernel.org, james.morse@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, arnd@arndb.de, akpm@linux-foundation.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, mhiramat@kernel.org, rppt@kernel.org, hughd@google.com Cc: pcc@google.com, steven.price@arm.com, anshuman.khandual@arm.com, vincenzo.frascino@arm.com, david@redhat.com, eugenis@google.com, kcc@google.com, hyesoo.yu@samsung.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH RFC v3 31/35] khugepaged: arm64: Don't collapse MTE enabled VMAs Date: Thu, 25 Jan 2024 16:42:52 +0000 Message-Id: <20240125164256.4147-32-alexandru.elisei@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240125164256.4147-1-alexandru.elisei@arm.com> References: <20240125164256.4147-1-alexandru.elisei@arm.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 copy_user_highpage() will do memory allocation if there are saved tags for the destination page, and the page is missing tag storage. After commit a349d72fd9ef ("mm/pgtable: add rcu_read_lock() and rcu_read_unlock()s"), collapse_huge_page() calls __collapse_huge_page_copy() -> .. -> copy_user_highpage() with the RCU lock held, which means that copy_user_highpage() can only allocate memory using GFP_ATOMIC or equivalent. Get around this by refusing to collapse pages into a transparent huge page if the VMA is MTE-enabled. Signed-off-by: Alexandru Elisei --- Changes since rfc v2: * New patch. I think an agreement on whether copy*_user_highpage() should be always allowed to sleep, or should not be allowed, would be useful. arch/arm64/include/asm/pgtable.h | 3 +++ arch/arm64/kernel/mte_tag_storage.c | 5 +++++ include/linux/khugepaged.h | 5 +++++ mm/khugepaged.c | 4 ++++ 4 files changed, 17 insertions(+) diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index 87ae59436162..d0473538c926 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -1120,6 +1120,9 @@ static inline bool arch_alloc_cma(gfp_t gfp_mask) return true; } +bool arch_hugepage_vma_revalidate(struct vm_area_struct *vma, unsigned long address); +#define arch_hugepage_vma_revalidate arch_hugepage_vma_revalidate + #endif /* CONFIG_ARM64_MTE_TAG_STORAGE */ #endif /* CONFIG_ARM64_MTE */ diff --git a/arch/arm64/kernel/mte_tag_storage.c b/arch/arm64/kernel/mte_tag_storage.c index ac7b9c9c585c..a99959b70573 100644 --- a/arch/arm64/kernel/mte_tag_storage.c +++ b/arch/arm64/kernel/mte_tag_storage.c @@ -636,3 +636,8 @@ void arch_alloc_page(struct page *page, int order, gfp_t gfp) if (tag_storage_enabled() && alloc_requires_tag_storage(gfp)) reserve_tag_storage(page, order, gfp); } + +bool arch_hugepage_vma_revalidate(struct vm_area_struct *vma, unsigned long address) +{ + return !(vma->vm_flags & VM_MTE); +} diff --git a/include/linux/khugepaged.h b/include/linux/khugepaged.h index f68865e19b0b..461e4322dff2 100644 --- a/include/linux/khugepaged.h +++ b/include/linux/khugepaged.h @@ -38,6 +38,11 @@ static inline void khugepaged_exit(struct mm_struct *mm) if (test_bit(MMF_VM_HUGEPAGE, &mm->flags)) __khugepaged_exit(mm); } + +#ifndef arch_hugepage_vma_revalidate +#define arch_hugepage_vma_revalidate(vma, address) 1 +#endif + #else /* CONFIG_TRANSPARENT_HUGEPAGE */ static inline void khugepaged_fork(struct mm_struct *mm, struct mm_struct *oldmm) { diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 2b219acb528e..cb9a9ddb4d86 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -935,6 +935,10 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, */ if (expect_anon && (!(*vmap)->anon_vma || !vma_is_anonymous(*vmap))) return SCAN_PAGE_ANON; + + if (!arch_hugepage_vma_revalidate(vma, address)) + return SCAN_VMA_CHECK; + return SCAN_SUCCEED; }