From: Jérôme Glisse <jglisse@xxxxxxxxxx> Subject: mm/hmm: do not differentiate between empty entry or missing directory There is no point in differentiating between a range for which there is not even a directory (and thus entries) and empty entry (pte_none() or pmd_none() returns true). Simply drop the distinction ie remove HMM_PFN_EMPTY flag and merge now duplicate hmm_vma_walk_hole() and hmm_vma_walk_clear() functions. Link: http://lkml.kernel.org/r/20180323005527.758-11-jglisse@xxxxxxxxxx Signed-off-by: Jérôme Glisse <jglisse@xxxxxxxxxx> Reviewed-by: John Hubbard <jhubbard@xxxxxxxxxx> Cc: Evgeny Baskakov <ebaskakov@xxxxxxxxxx> Cc: Ralph Campbell <rcampbell@xxxxxxxxxx> Cc: Mark Hairgrove <mhairgrove@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/hmm.h | 8 ++----- mm/hmm.c | 45 ++++++++++++++---------------------------- 2 files changed, 18 insertions(+), 35 deletions(-) diff -puN include/linux/hmm.h~mm-hmm-do-not-differentiate-between-empty-entry-or-missing-directory-v3 include/linux/hmm.h --- a/include/linux/hmm.h~mm-hmm-do-not-differentiate-between-empty-entry-or-missing-directory-v3 +++ a/include/linux/hmm.h @@ -84,7 +84,6 @@ struct hmm; * HMM_PFN_VALID: pfn is valid. It has, at least, read permission. * HMM_PFN_WRITE: CPU page table has write permission set * HMM_PFN_ERROR: corresponding CPU page table entry points to poisoned memory - * HMM_PFN_EMPTY: corresponding CPU page table entry is pte_none() * HMM_PFN_SPECIAL: corresponding CPU page table entry is special; i.e., the * result of vm_insert_pfn() or vm_insert_page(). Therefore, it should not * be mirrored by a device, because the entry will never have HMM_PFN_VALID @@ -94,10 +93,9 @@ struct hmm; #define HMM_PFN_VALID (1 << 0) #define HMM_PFN_WRITE (1 << 1) #define HMM_PFN_ERROR (1 << 2) -#define HMM_PFN_EMPTY (1 << 3) -#define HMM_PFN_SPECIAL (1 << 4) -#define HMM_PFN_DEVICE_UNADDRESSABLE (1 << 5) -#define HMM_PFN_SHIFT 6 +#define HMM_PFN_SPECIAL (1 << 3) +#define HMM_PFN_DEVICE_UNADDRESSABLE (1 << 4) +#define HMM_PFN_SHIFT 5 /* * hmm_pfn_to_page() - return struct page pointed to by a valid HMM pfn diff -puN mm/hmm.c~mm-hmm-do-not-differentiate-between-empty-entry-or-missing-directory-v3 mm/hmm.c --- a/mm/hmm.c~mm-hmm-do-not-differentiate-between-empty-entry-or-missing-directory-v3 +++ a/mm/hmm.c @@ -348,6 +348,16 @@ static void hmm_pfns_clear(uint64_t *pfn *pfns = 0; } +/* + * hmm_vma_walk_hole() - handle a range lacking valid pmd or pte(s) + * @start: range virtual start address (inclusive) + * @end: range virtual end address (exclusive) + * @walk: mm_walk structure + * Returns: 0 on success, -EAGAIN after page fault, or page fault error + * + * This function will be called whenever pmd_none() or pte_none() returns true, + * or whenever there is no page directory covering the virtual address range. + */ static int hmm_vma_walk_hole(unsigned long addr, unsigned long end, struct mm_walk *walk) @@ -360,31 +370,6 @@ static int hmm_vma_walk_hole(unsigned lo hmm_vma_walk->last = addr; i = (addr - range->start) >> PAGE_SHIFT; for (; addr < end; addr += PAGE_SIZE, i++) { - pfns[i] = HMM_PFN_EMPTY; - if (hmm_vma_walk->fault) { - int ret; - - ret = hmm_vma_do_fault(walk, addr, &pfns[i]); - if (ret != -EAGAIN) - return ret; - } - } - - return hmm_vma_walk->fault ? -EAGAIN : 0; -} - -static int hmm_vma_walk_clear(unsigned long addr, - unsigned long end, - struct mm_walk *walk) -{ - struct hmm_vma_walk *hmm_vma_walk = walk->private; - struct hmm_range *range = hmm_vma_walk->range; - uint64_t *pfns = range->pfns; - unsigned long i; - - hmm_vma_walk->last = addr; - i = (addr - range->start) >> PAGE_SHIFT; - for (; addr < end; addr += PAGE_SIZE, i++) { pfns[i] = 0; if (hmm_vma_walk->fault) { int ret; @@ -440,10 +425,10 @@ again: if (!pmd_devmap(pmd) && !pmd_trans_huge(pmd)) goto again; if (pmd_protnone(pmd)) - return hmm_vma_walk_clear(start, end, walk); + return hmm_vma_walk_hole(start, end, walk); if (write_fault && !pmd_write(pmd)) - return hmm_vma_walk_clear(start, end, walk); + return hmm_vma_walk_hole(start, end, walk); pfn = pmd_pfn(pmd) + pte_index(addr); flag |= pmd_write(pmd) ? HMM_PFN_WRITE : 0; @@ -462,7 +447,7 @@ again: pfns[i] = 0; if (pte_none(pte)) { - pfns[i] = HMM_PFN_EMPTY; + pfns[i] = 0; if (hmm_vma_walk->fault) goto fault; continue; @@ -513,8 +498,8 @@ again: fault: pte_unmap(ptep); - /* Fault all pages in range */ - return hmm_vma_walk_clear(start, end, walk); + /* Fault any virtual address we were asked to fault */ + return hmm_vma_walk_hole(start, end, walk); } pte_unmap(ptep - 1); _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
