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mm/hugetlb: enforce that PMD PT sharing has split PMD PT locks

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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.

Link: https://lkml.kernel.org/r/20240726150728.3159964-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
David Hildenbrand 2024-07-26 17:07:27 +02:00 committed by Andrew Morton
parent 394290cba9
commit 188cac58a8
3 changed files with 10 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
fs/Kconfig
View File

@ -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
bool

5
include/linux/hugetlb.h
View File

@ -1251,7 +1251,7 @@ 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;
@ -1287,8 +1287,7 @@ 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;
/*

8
mm/hugetlb.c
View File

@ -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