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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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033193275b
Right now, if a mm_walk has either ->pte_entry or ->pmd_entry set, it will unconditionally split any transparent huge pages it runs in to. In practice, that means that anyone doing a cat /proc/$pid/smaps will unconditionally break down every huge page in the process and depend on khugepaged to re-collapse it later. This is fairly suboptimal. This patch changes that behavior. It teaches each ->pmd_entry handler (there are five) that they must break down the THPs themselves. Also, the _generic_ code will never break down a THP unless a ->pte_entry handler is actually set. This means that the ->pmd_entry handlers can now choose to deal with THPs without breaking them down. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Acked-by: David Rientjes <rientjes@google.com> Reviewed-by: Eric B Munson <emunson@mgebm.net> Tested-by: Eric B Munson <emunson@mgebm.net> Cc: Michael J Wolf <mjwolf@us.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Matt Mackall <mpm@selenic.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
213 lines
5.0 KiB
C
213 lines
5.0 KiB
C
#include <linux/mm.h>
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#include <linux/highmem.h>
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#include <linux/sched.h>
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#include <linux/hugetlb.h>
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static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
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struct mm_walk *walk)
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{
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pte_t *pte;
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int err = 0;
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pte = pte_offset_map(pmd, addr);
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for (;;) {
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err = walk->pte_entry(pte, addr, addr + PAGE_SIZE, walk);
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if (err)
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break;
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addr += PAGE_SIZE;
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if (addr == end)
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break;
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pte++;
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}
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pte_unmap(pte);
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return err;
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}
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static int walk_pmd_range(pud_t *pud, unsigned long addr, unsigned long end,
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struct mm_walk *walk)
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{
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pmd_t *pmd;
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unsigned long next;
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int err = 0;
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pmd = pmd_offset(pud, addr);
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do {
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again:
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next = pmd_addr_end(addr, end);
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if (pmd_none(*pmd)) {
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if (walk->pte_hole)
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err = walk->pte_hole(addr, next, walk);
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if (err)
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break;
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continue;
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}
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/*
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* This implies that each ->pmd_entry() handler
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* needs to know about pmd_trans_huge() pmds
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*/
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if (walk->pmd_entry)
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err = walk->pmd_entry(pmd, addr, next, walk);
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if (err)
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break;
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/*
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* Check this here so we only break down trans_huge
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* pages when we _need_ to
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*/
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if (!walk->pte_entry)
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continue;
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split_huge_page_pmd(walk->mm, pmd);
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if (pmd_none_or_clear_bad(pmd))
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goto again;
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err = walk_pte_range(pmd, addr, next, walk);
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if (err)
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break;
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} while (pmd++, addr = next, addr != end);
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return err;
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}
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static int walk_pud_range(pgd_t *pgd, unsigned long addr, unsigned long end,
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struct mm_walk *walk)
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{
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pud_t *pud;
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unsigned long next;
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int err = 0;
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pud = pud_offset(pgd, addr);
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do {
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next = pud_addr_end(addr, end);
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if (pud_none_or_clear_bad(pud)) {
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if (walk->pte_hole)
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err = walk->pte_hole(addr, next, walk);
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if (err)
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break;
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continue;
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}
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if (walk->pud_entry)
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err = walk->pud_entry(pud, addr, next, walk);
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if (!err && (walk->pmd_entry || walk->pte_entry))
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err = walk_pmd_range(pud, addr, next, walk);
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if (err)
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break;
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} while (pud++, addr = next, addr != end);
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return err;
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}
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#ifdef CONFIG_HUGETLB_PAGE
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static unsigned long hugetlb_entry_end(struct hstate *h, unsigned long addr,
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unsigned long end)
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{
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unsigned long boundary = (addr & huge_page_mask(h)) + huge_page_size(h);
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return boundary < end ? boundary : end;
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}
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static int walk_hugetlb_range(struct vm_area_struct *vma,
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unsigned long addr, unsigned long end,
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struct mm_walk *walk)
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{
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struct hstate *h = hstate_vma(vma);
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unsigned long next;
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unsigned long hmask = huge_page_mask(h);
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pte_t *pte;
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int err = 0;
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do {
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next = hugetlb_entry_end(h, addr, end);
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pte = huge_pte_offset(walk->mm, addr & hmask);
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if (pte && walk->hugetlb_entry)
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err = walk->hugetlb_entry(pte, hmask, addr, next, walk);
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if (err)
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return err;
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} while (addr = next, addr != end);
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return 0;
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}
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#endif
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/**
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* walk_page_range - walk a memory map's page tables with a callback
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* @mm: memory map to walk
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* @addr: starting address
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* @end: ending address
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* @walk: set of callbacks to invoke for each level of the tree
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*
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* Recursively walk the page table for the memory area in a VMA,
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* calling supplied callbacks. Callbacks are called in-order (first
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* PGD, first PUD, first PMD, first PTE, second PTE... second PMD,
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* etc.). If lower-level callbacks are omitted, walking depth is reduced.
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*
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* Each callback receives an entry pointer and the start and end of the
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* associated range, and a copy of the original mm_walk for access to
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* the ->private or ->mm fields.
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*
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* No locks are taken, but the bottom level iterator will map PTE
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* directories from highmem if necessary.
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*
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* If any callback returns a non-zero value, the walk is aborted and
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* the return value is propagated back to the caller. Otherwise 0 is returned.
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*/
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int walk_page_range(unsigned long addr, unsigned long end,
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struct mm_walk *walk)
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{
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pgd_t *pgd;
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unsigned long next;
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int err = 0;
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if (addr >= end)
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return err;
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if (!walk->mm)
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return -EINVAL;
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pgd = pgd_offset(walk->mm, addr);
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do {
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struct vm_area_struct *uninitialized_var(vma);
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next = pgd_addr_end(addr, end);
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#ifdef CONFIG_HUGETLB_PAGE
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/*
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* handle hugetlb vma individually because pagetable walk for
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* the hugetlb page is dependent on the architecture and
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* we can't handled it in the same manner as non-huge pages.
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*/
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vma = find_vma(walk->mm, addr);
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if (vma && is_vm_hugetlb_page(vma)) {
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if (vma->vm_end < next)
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next = vma->vm_end;
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/*
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* Hugepage is very tightly coupled with vma, so
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* walk through hugetlb entries within a given vma.
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*/
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err = walk_hugetlb_range(vma, addr, next, walk);
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if (err)
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break;
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pgd = pgd_offset(walk->mm, next);
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continue;
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}
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#endif
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if (pgd_none_or_clear_bad(pgd)) {
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if (walk->pte_hole)
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err = walk->pte_hole(addr, next, walk);
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if (err)
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break;
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pgd++;
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continue;
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}
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if (walk->pgd_entry)
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err = walk->pgd_entry(pgd, addr, next, walk);
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if (!err &&
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(walk->pud_entry || walk->pmd_entry || walk->pte_entry))
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err = walk_pud_range(pgd, addr, next, walk);
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if (err)
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break;
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pgd++;
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} while (addr = next, addr != end);
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return err;
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}
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