| Message ID | 20140520004429.E660AE009B@blue.fi.intel.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> writes: > Andrew Morton wrote: >> On Mon, 19 May 2014 16:23:07 -0700 (PDT) Hugh Dickins <hughd@google.com> wrote: >> >> > Shouldn't FAULT_AROUND_ORDER and fault_around_order be changed to be >> > the order of the fault-around size in bytes, and fault_around_pages() >> > use 1UL << (fault_around_order - PAGE_SHIFT) >> >> Yes. And shame on me for missing it (this time!) at review. >> >> There's still time to fix this. Patches, please. > > Here it is. Made at 3.30 AM, build tested only. Prefer on top of Maddy's patch which makes it always a variable, rather than CONFIG_DEBUG_FS. It's got enough hair as it is. Cheers, Rusty.
On Tue, 20 May 2014 15:52:07 +0930 Rusty Russell <rusty@rustcorp.com.au> wrote: > "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> writes: > > Andrew Morton wrote: > >> On Mon, 19 May 2014 16:23:07 -0700 (PDT) Hugh Dickins <hughd@google.com> wrote: > >> > >> > Shouldn't FAULT_AROUND_ORDER and fault_around_order be changed to be > >> > the order of the fault-around size in bytes, and fault_around_pages() > >> > use 1UL << (fault_around_order - PAGE_SHIFT) > >> > >> Yes. And shame on me for missing it (this time!) at review. > >> > >> There's still time to fix this. Patches, please. > > > > Here it is. Made at 3.30 AM, build tested only. > > Prefer on top of Maddy's patch which makes it always a variable, rather > than CONFIG_DEBUG_FS. It's got enough hair as it is. > We're at 3.15-rc5 and this interface should be finalised for 3.16. So Kirrill's patch is pretty urgent and should come first. Well. It's only a debugfs interface at this stage so we are allowed to change it later, but it's better not to.
On Tuesday 20 May 2014 01:02 PM, Andrew Morton wrote: > On Tue, 20 May 2014 15:52:07 +0930 Rusty Russell <rusty@rustcorp.com.au> wrote: > >> "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> writes: >>> Andrew Morton wrote: >>>> On Mon, 19 May 2014 16:23:07 -0700 (PDT) Hugh Dickins <hughd@google.com> wrote: >>>> >>>>> Shouldn't FAULT_AROUND_ORDER and fault_around_order be changed to be >>>>> the order of the fault-around size in bytes, and fault_around_pages() >>>>> use 1UL << (fault_around_order - PAGE_SHIFT) >>>> >>>> Yes. And shame on me for missing it (this time!) at review. >>>> >>>> There's still time to fix this. Patches, please. >>> >>> Here it is. Made at 3.30 AM, build tested only. >> >> Prefer on top of Maddy's patch which makes it always a variable, rather >> than CONFIG_DEBUG_FS. It's got enough hair as it is. >> > > We're at 3.15-rc5 and this interface should be finalised for 3.16. So > Kirrill's patch is pretty urgent and should come first. > > Well. It's only a debugfs interface at this stage so we are allowed to > change it later, but it's better not to. > My patchset does not change the interface, but uses the current fault around order variable from CONFIG_DEBUG_FS block to allow changes at runtime, instead of having a constant and some cleanup. Thanks for review Regards --Maddy
diff --git a/mm/memory.c b/mm/memory.c index 037b812a9531..9d6941c9a9e4 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -3402,62 +3402,62 @@ void do_set_pte(struct vm_area_struct *vma, unsigned long address, update_mmu_cache(vma, address, pte); } -#define FAULT_AROUND_ORDER 4 +#define FAULT_AROUND_BYTES 65536 #ifdef CONFIG_DEBUG_FS -static unsigned int fault_around_order = FAULT_AROUND_ORDER; +static unsigned int fault_around_bytes = FAULT_AROUND_BYTES; -static int fault_around_order_get(void *data, u64 *val) +static int fault_around_bytes_get(void *data, u64 *val) { - *val = fault_around_order; + *val = fault_around_bytes; return 0; } -static int fault_around_order_set(void *data, u64 val) +static int fault_around_bytes_set(void *data, u64 val) { - BUILD_BUG_ON((1UL << FAULT_AROUND_ORDER) > PTRS_PER_PTE); - if (1UL << val > PTRS_PER_PTE) + BUILD_BUG_ON(FAULT_AROUND_BYTES / PAGE_SIZE > PTRS_PER_PTE); + if (val / PAGE_SIZE > PTRS_PER_PTE) return -EINVAL; - fault_around_order = val; + fault_around_bytes = val; return 0; } -DEFINE_SIMPLE_ATTRIBUTE(fault_around_order_fops, - fault_around_order_get, fault_around_order_set, "%llu\n"); +DEFINE_SIMPLE_ATTRIBUTE(fault_around_bytes_fops, + fault_around_bytes_get, fault_around_bytes_set, "%llu\n"); static int __init fault_around_debugfs(void) { void *ret; - ret = debugfs_create_file("fault_around_order", 0644, NULL, NULL, - &fault_around_order_fops); + ret = debugfs_create_file("fault_around_bytes", 0644, NULL, NULL, + &fault_around_bytes_fops); if (!ret) - pr_warn("Failed to create fault_around_order in debugfs"); + pr_warn("Failed to create fault_around_bytes in debugfs"); return 0; } late_initcall(fault_around_debugfs); static inline unsigned long fault_around_pages(void) { - return 1UL << fault_around_order; + return fault_around_bytes / PAGE_SIZE; } static inline unsigned long fault_around_mask(void) { - return ~((1UL << (PAGE_SHIFT + fault_around_order)) - 1); + return ~(round_down(fault_around_bytes, PAGE_SIZE) - 1); } #else static inline unsigned long fault_around_pages(void) { unsigned long nr_pages; - nr_pages = 1UL << FAULT_AROUND_ORDER; + nr_pages = FAULT_AROUND_BYTES / PAGE_SIZE; BUILD_BUG_ON(nr_pages > PTRS_PER_PTE); return nr_pages; } static inline unsigned long fault_around_mask(void) { - return ~((1UL << (PAGE_SHIFT + FAULT_AROUND_ORDER)) - 1); + return ~(round_down(FAULT_AROUND_BYTES, PAGE_SIZE) - 1); } #endif @@ -3515,7 +3515,7 @@ static int do_read_fault(struct mm_struct *mm, struct vm_area_struct *vma, * if page by the offset is not ready to be mapped (cold cache or * something). */ - if (vma->vm_ops->map_pages) { + if (vma->vm_ops->map_pages && fault_around_pages() > 1) { pte = pte_offset_map_lock(mm, pmd, address, &ptl); do_fault_around(vma, address, pte, pgoff, flags); if (!pte_same(*pte, orig_pte))