Re: [PATCH] mm: Track page table modifications in __apply_to_page_range() construction

Greg KH
2020-08-21T10:53:23Z

On Fri, Aug 21, 2020 at 12:09:02PM +0200, Joerg Roedel wrote:
> The __apply_to_page_range() function is also used to change and/or
> allocate page-table pages in the vmalloc area of the address space.
> Make sure these changes get synchronized to other page-tables in the
> system by calling arch_sync_kernel_mappings() when necessary.
>
> Signed-off-by: Joerg Roedel <jroedel@suse.de>
> ---
> (Only compile tested on x86-64 so far)
>
> mm/memory.c | 32 +++++++++++++++++++++-----------
> 1 file changed, 21 insertions(+), 11 deletions(-)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 3a7779d9891d..fd845991f14a 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -83,6 +83,7 @@
> #include <asm/tlb.h>
> #include <asm/tlbflush.h>
>
> +#include "pgalloc-track.h"
> #include "internal.h"
>
> #if defined(LAST_CPUPID_NOT_IN_PAGE_FLAGS) && !defined(CONFIG_COMPILE_TEST)
> @@ -2206,7 +2207,8 @@ EXPORT_SYMBOL(vm_iomap_memory);
>
> static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
> unsigned long addr, unsigned long end,
> - pte_fn_t fn, void *data, bool create)
> + pte_fn_t fn, void *data, bool create,
> + pgtbl_mod_mask *mask)
> {
> pte_t *pte;
> int err = 0;
> @@ -2235,6 +2237,7 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
> break;
> }
> } while (addr += PAGE_SIZE, addr != end);
> + *mask |= PGTBL_PTE_MODIFIED;
>
> arch_leave_lazy_mmu_mode();
>
> @@ -2245,7 +2248,8 @@ static int apply_to_pte_range(struct mm_struct *mm, pmd_t *pmd,
>
> static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
> unsigned long addr, unsigned long end,
> - pte_fn_t fn, void *data, bool create)
> + pte_fn_t fn, void *data, bool create,
> + pgtbl_mod_mask *mask)
> {
> pmd_t *pmd;
> unsigned long next;
> @@ -2254,7 +2258,7 @@ static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
> BUG_ON(pud_huge(*pud));
>
> if (create) {
> - pmd = pmd_alloc(mm, pud, addr);
> + pmd = pmd_alloc_track(mm, pud, addr, mask);
> if (!pmd)
> return -ENOMEM;
> } else {
> @@ -2264,7 +2268,7 @@ static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
> next = pmd_addr_end(addr, end);
> if (create || !pmd_none_or_clear_bad(pmd)) {
> err = apply_to_pte_range(mm, pmd, addr, next, fn, data,
> - create);
> + create, mask);
> if (err)
> break;
> }
> @@ -2274,14 +2278,15 @@ static int apply_to_pmd_range(struct mm_struct *mm, pud_t *pud,
>
> static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
> unsigned long addr, unsigned long end,
> - pte_fn_t fn, void *data, bool create)
> + pte_fn_t fn, void *data, bool create,
> + pgtbl_mod_mask *mask)
> {
> pud_t *pud;
> unsigned long next;
> int err = 0;
>
> if (create) {
> - pud = pud_alloc(mm, p4d, addr);
> + pud = pud_alloc_track(mm, p4d, addr, mask);
> if (!pud)
> return -ENOMEM;
> } else {
> @@ -2291,7 +2296,7 @@ static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
> next = pud_addr_end(addr, end);
> if (create || !pud_none_or_clear_bad(pud)) {
> err = apply_to_pmd_range(mm, pud, addr, next, fn, data,
> - create);
> + create, mask);
> if (err)
> break;
> }
> @@ -2301,14 +2306,15 @@ static int apply_to_pud_range(struct mm_struct *mm, p4d_t *p4d,
>
> static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
> unsigned long addr, unsigned long end,
> - pte_fn_t fn, void *data, bool create)
> + pte_fn_t fn, void *data, bool create,
> + pgtbl_mod_mask *mask)
> {
> p4d_t *p4d;
> unsigned long next;
> int err = 0;
>
> if (create) {
> - p4d = p4d_alloc(mm, pgd, addr);
> + p4d = p4d_alloc_track(mm, pgd, addr, mask);
> if (!p4d)
> return -ENOMEM;
> } else {
> @@ -2318,7 +2324,7 @@ static int apply_to_p4d_range(struct mm_struct *mm, pgd_t *pgd,
> next = p4d_addr_end(addr, end);
> if (create || !p4d_none_or_clear_bad(p4d)) {
> err = apply_to_pud_range(mm, p4d, addr, next, fn, data,
> - create);
> + create, mask);
> if (err)
> break;
> }
> @@ -2333,6 +2339,7 @@ static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr,
> pgd_t *pgd;
> unsigned long next;
> unsigned long end = addr + size;
> + pgtbl_mod_mask mask = 0;
> int err = 0;
>
> if (WARN_ON(addr >= end))
> @@ -2343,11 +2350,14 @@ static int __apply_to_page_range(struct mm_struct *mm, unsigned long addr,
> next = pgd_addr_end(addr, end);
> if (!create && pgd_none_or_clear_bad(pgd))
> continue;
> - err = apply_to_p4d_range(mm, pgd, addr, next, fn, data, create);
> + err = apply_to_p4d_range(mm, pgd, addr, next, fn, data, create, &mask);
> if (err)
> break;
> } while (pgd++, addr = next, addr != end);
>
> + if (mask & ARCH_PAGE_TABLE_SYNC_MASK)
> + arch_sync_kernel_mappings(addr, addr + size);
> +
> return err;
> }
>
> --
> 2.28.0
>

<formletter>

This is not the correct way to submit patches for inclusion in the
stable kernel tree. Please read:
https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html
for how to do this properly.