Re: [PATCH v1 2/3] mm/hugetlb: enforce that PMD PT sharing has split PMD PT locks
From: Mike Rapoport <rppt@kernel.org>
Date: 2024-07-28 12:47:42
Also in:
linux-arm-kernel, linux-fsdevel, linux-mm, lkml, xen-devel
On Fri, Jul 26, 2024 at 05:07:27PM +0200, David Hildenbrand wrote:
Sharing page tables between processes but falling back to per-MM page table locks cannot possibly work. So, let's make sure that we do have split PMD locks by adding a new Kconfig option and letting that depend on CONFIG_SPLIT_PMD_PTLOCKS. Signed-off-by: David Hildenbrand <redacted>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
quoted hunk ↗ jump to hunk
--- fs/Kconfig | 4 ++++ include/linux/hugetlb.h | 5 ++--- mm/hugetlb.c | 8 ++++---- 3 files changed, 10 insertions(+), 7 deletions(-)diff --git a/fs/Kconfig b/fs/Kconfig index a46b0cbc4d8f6..0e4efec1d92e6 100644 --- a/fs/Kconfig +++ b/fs/Kconfig@@ -288,6 +288,10 @@ config HUGETLB_PAGE_OPTIMIZE_VMEMMAP depends on ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP depends on SPARSEMEM_VMEMMAP +config HUGETLB_PMD_PAGE_TABLE_SHARING + def_bool HUGETLB_PAGE + depends on ARCH_WANT_HUGE_PMD_SHARE && SPLIT_PMD_PTLOCKS + config ARCH_HAS_GIGANTIC_PAGE booldiff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index da800e56fe590..4d2f3224ff027 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h@@ -1243,7 +1243,7 @@ static inline __init void hugetlb_cma_reserve(int order) } #endif -#ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE +#ifdef CONFIG_HUGETLB_PMD_PAGE_TABLE_SHARING static inline bool hugetlb_pmd_shared(pte_t *pte) { return page_count(virt_to_page(pte)) > 1;@@ -1279,8 +1279,7 @@ bool __vma_private_lock(struct vm_area_struct *vma); static inline pte_t * hugetlb_walk(struct vm_area_struct *vma, unsigned long addr, unsigned long sz) { -#if defined(CONFIG_HUGETLB_PAGE) && \ - defined(CONFIG_ARCH_WANT_HUGE_PMD_SHARE) && defined(CONFIG_LOCKDEP) +#if defined(CONFIG_HUGETLB_PMD_PAGE_TABLE_SHARING) && defined(CONFIG_LOCKDEP) struct hugetlb_vma_lock *vma_lock = vma->vm_private_data; /*diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 0858a18272073..c4d94e122c41f 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c@@ -7211,7 +7211,7 @@ long hugetlb_unreserve_pages(struct inode *inode, long start, long end, return 0; } -#ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE +#ifdef CONFIG_HUGETLB_PMD_PAGE_TABLE_SHARING static unsigned long page_table_shareable(struct vm_area_struct *svma, struct vm_area_struct *vma, unsigned long addr, pgoff_t idx)@@ -7373,7 +7373,7 @@ int huge_pmd_unshare(struct mm_struct *mm, struct vm_area_struct *vma, return 1; } -#else /* !CONFIG_ARCH_WANT_HUGE_PMD_SHARE */ +#else /* !CONFIG_HUGETLB_PMD_PAGE_TABLE_SHARING */ pte_t *huge_pmd_share(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, pud_t *pud)@@ -7396,7 +7396,7 @@ bool want_pmd_share(struct vm_area_struct *vma, unsigned long addr) { return false; } -#endif /* CONFIG_ARCH_WANT_HUGE_PMD_SHARE */ +#endif /* CONFIG_HUGETLB_PMD_PAGE_TABLE_SHARING */ #ifdef CONFIG_ARCH_WANT_GENERAL_HUGETLB pte_t *huge_pte_alloc(struct mm_struct *mm, struct vm_area_struct *vma,@@ -7494,7 +7494,7 @@ unsigned long hugetlb_mask_last_page(struct hstate *h) /* See description above. Architectures can provide their own version. */ __weak unsigned long hugetlb_mask_last_page(struct hstate *h) { -#ifdef CONFIG_ARCH_WANT_HUGE_PMD_SHARE +#ifdef CONFIG_HUGETLB_PMD_PAGE_TABLE_SHARING if (huge_page_size(h) == PMD_SIZE) return PUD_SIZE - PMD_SIZE; #endif-- 2.45.2
-- Sincerely yours, Mike.