Revision c4f675cd40d955d539180506c09515c90169b15b authored by Sergei Trofimovich on 20 May 2011, 20:20:30 UTC, committed by Chris Mason on 23 May 2011, 17:24:14 UTC
Observed as a large delay when --mixed filesystem is filled up. Test example: 1. create tiny --mixed FS: $ dd if=/dev/zero of=2G.img seek=$((2048 * 1024 * 1024 - 1)) count=1 bs=1 $ mkfs.btrfs --mixed 2G.img $ mount -oloop 2G.img /mnt/ut/ 2. Try to fill it up: $ dd if=/dev/urandom of=10M.file bs=10240 count=1024 $ seq 1 256 | while read file_no; do echo $file_no; time cp 10M.file ${file_no}.copy; done Up to '200.copy' it goes fast, but when disk fills-up each -ENOSPC message takes 3 seconds to pop-up _every_ ENOSPC (and in usermode linux it's even more: 30-60 seconds!). (Maybe, time depends on kernel's timer resolution). No IO, no CPU load, just rescheduling. Some debugging revealed busy spinning in shrink_delalloc. Signed-off-by: Sergei Trofimovich <slyfox@gentoo.org> Reviewed-by: Josef Bacik <josef@redhat.com> Signed-off-by: Chris Mason <chris.mason@oracle.com>
1 parent 0f3b708
init.c
/*
* linux/arch/alpha/mm/init.c
*
* Copyright (C) 1995 Linus Torvalds
*/
/* 2.3.x zone allocator, 1999 Andrea Arcangeli <andrea@suse.de> */
#include <linux/pagemap.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/ptrace.h>
#include <linux/mman.h>
#include <linux/mm.h>
#include <linux/swap.h>
#include <linux/init.h>
#include <linux/bootmem.h> /* max_low_pfn */
#include <linux/vmalloc.h>
#include <linux/gfp.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/pgalloc.h>
#include <asm/hwrpb.h>
#include <asm/dma.h>
#include <asm/mmu_context.h>
#include <asm/console.h>
#include <asm/tlb.h>
DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
extern void die_if_kernel(char *,struct pt_regs *,long);
static struct pcb_struct original_pcb;
pgd_t *
pgd_alloc(struct mm_struct *mm)
{
pgd_t *ret, *init;
ret = (pgd_t *)__get_free_page(GFP_KERNEL | __GFP_ZERO);
init = pgd_offset(&init_mm, 0UL);
if (ret) {
#ifdef CONFIG_ALPHA_LARGE_VMALLOC
memcpy (ret + USER_PTRS_PER_PGD, init + USER_PTRS_PER_PGD,
(PTRS_PER_PGD - USER_PTRS_PER_PGD - 1)*sizeof(pgd_t));
#else
pgd_val(ret[PTRS_PER_PGD-2]) = pgd_val(init[PTRS_PER_PGD-2]);
#endif
/* The last PGD entry is the VPTB self-map. */
pgd_val(ret[PTRS_PER_PGD-1])
= pte_val(mk_pte(virt_to_page(ret), PAGE_KERNEL));
}
return ret;
}
/*
* BAD_PAGE is the page that is used for page faults when linux
* is out-of-memory. Older versions of linux just did a
* do_exit(), but using this instead means there is less risk
* for a process dying in kernel mode, possibly leaving an inode
* unused etc..
*
* BAD_PAGETABLE is the accompanying page-table: it is initialized
* to point to BAD_PAGE entries.
*
* ZERO_PAGE is a special page that is used for zero-initialized
* data and COW.
*/
pmd_t *
__bad_pagetable(void)
{
memset((void *) EMPTY_PGT, 0, PAGE_SIZE);
return (pmd_t *) EMPTY_PGT;
}
pte_t
__bad_page(void)
{
memset((void *) EMPTY_PGE, 0, PAGE_SIZE);
return pte_mkdirty(mk_pte(virt_to_page(EMPTY_PGE), PAGE_SHARED));
}
static inline unsigned long
load_PCB(struct pcb_struct *pcb)
{
register unsigned long sp __asm__("$30");
pcb->ksp = sp;
return __reload_thread(pcb);
}
/* Set up initial PCB, VPTB, and other such nicities. */
static inline void
switch_to_system_map(void)
{
unsigned long newptbr;
unsigned long original_pcb_ptr;
/* Initialize the kernel's page tables. Linux puts the vptb in
the last slot of the L1 page table. */
memset(swapper_pg_dir, 0, PAGE_SIZE);
newptbr = ((unsigned long) swapper_pg_dir - PAGE_OFFSET) >> PAGE_SHIFT;
pgd_val(swapper_pg_dir[1023]) =
(newptbr << 32) | pgprot_val(PAGE_KERNEL);
/* Set the vptb. This is often done by the bootloader, but
shouldn't be required. */
if (hwrpb->vptb != 0xfffffffe00000000UL) {
wrvptptr(0xfffffffe00000000UL);
hwrpb->vptb = 0xfffffffe00000000UL;
hwrpb_update_checksum(hwrpb);
}
/* Also set up the real kernel PCB while we're at it. */
init_thread_info.pcb.ptbr = newptbr;
init_thread_info.pcb.flags = 1; /* set FEN, clear everything else */
original_pcb_ptr = load_PCB(&init_thread_info.pcb);
tbia();
/* Save off the contents of the original PCB so that we can
restore the original console's page tables for a clean reboot.
Note that the PCB is supposed to be a physical address, but
since KSEG values also happen to work, folks get confused.
Check this here. */
if (original_pcb_ptr < PAGE_OFFSET) {
original_pcb_ptr = (unsigned long)
phys_to_virt(original_pcb_ptr);
}
original_pcb = *(struct pcb_struct *) original_pcb_ptr;
}
int callback_init_done;
void * __init
callback_init(void * kernel_end)
{
struct crb_struct * crb;
pgd_t *pgd;
pmd_t *pmd;
void *two_pages;
/* Starting at the HWRPB, locate the CRB. */
crb = (struct crb_struct *)((char *)hwrpb + hwrpb->crb_offset);
if (alpha_using_srm) {
/* Tell the console whither it is to be remapped. */
if (srm_fixup(VMALLOC_START, (unsigned long)hwrpb))
__halt(); /* "We're boned." --Bender */
/* Edit the procedure descriptors for DISPATCH and FIXUP. */
crb->dispatch_va = (struct procdesc_struct *)
(VMALLOC_START + (unsigned long)crb->dispatch_va
- crb->map[0].va);
crb->fixup_va = (struct procdesc_struct *)
(VMALLOC_START + (unsigned long)crb->fixup_va
- crb->map[0].va);
}
switch_to_system_map();
/* Allocate one PGD and one PMD. In the case of SRM, we'll need
these to actually remap the console. There is an assumption
here that only one of each is needed, and this allows for 8MB.
On systems with larger consoles, additional pages will be
allocated as needed during the mapping process.
In the case of not SRM, but not CONFIG_ALPHA_LARGE_VMALLOC,
we need to allocate the PGD we use for vmalloc before we start
forking other tasks. */
two_pages = (void *)
(((unsigned long)kernel_end + ~PAGE_MASK) & PAGE_MASK);
kernel_end = two_pages + 2*PAGE_SIZE;
memset(two_pages, 0, 2*PAGE_SIZE);
pgd = pgd_offset_k(VMALLOC_START);
pgd_set(pgd, (pmd_t *)two_pages);
pmd = pmd_offset(pgd, VMALLOC_START);
pmd_set(pmd, (pte_t *)(two_pages + PAGE_SIZE));
if (alpha_using_srm) {
static struct vm_struct console_remap_vm;
unsigned long nr_pages = 0;
unsigned long vaddr;
unsigned long i, j;
/* calculate needed size */
for (i = 0; i < crb->map_entries; ++i)
nr_pages += crb->map[i].count;
/* register the vm area */
console_remap_vm.flags = VM_ALLOC;
console_remap_vm.size = nr_pages << PAGE_SHIFT;
vm_area_register_early(&console_remap_vm, PAGE_SIZE);
vaddr = (unsigned long)console_remap_vm.addr;
/* Set up the third level PTEs and update the virtual
addresses of the CRB entries. */
for (i = 0; i < crb->map_entries; ++i) {
unsigned long pfn = crb->map[i].pa >> PAGE_SHIFT;
crb->map[i].va = vaddr;
for (j = 0; j < crb->map[i].count; ++j) {
/* Newer consoles (especially on larger
systems) may require more pages of
PTEs. Grab additional pages as needed. */
if (pmd != pmd_offset(pgd, vaddr)) {
memset(kernel_end, 0, PAGE_SIZE);
pmd = pmd_offset(pgd, vaddr);
pmd_set(pmd, (pte_t *)kernel_end);
kernel_end += PAGE_SIZE;
}
set_pte(pte_offset_kernel(pmd, vaddr),
pfn_pte(pfn, PAGE_KERNEL));
pfn++;
vaddr += PAGE_SIZE;
}
}
}
callback_init_done = 1;
return kernel_end;
}
#ifndef CONFIG_DISCONTIGMEM
/*
* paging_init() sets up the memory map.
*/
void __init paging_init(void)
{
unsigned long zones_size[MAX_NR_ZONES] = {0, };
unsigned long dma_pfn, high_pfn;
dma_pfn = virt_to_phys((char *)MAX_DMA_ADDRESS) >> PAGE_SHIFT;
high_pfn = max_pfn = max_low_pfn;
if (dma_pfn >= high_pfn)
zones_size[ZONE_DMA] = high_pfn;
else {
zones_size[ZONE_DMA] = dma_pfn;
zones_size[ZONE_NORMAL] = high_pfn - dma_pfn;
}
/* Initialize mem_map[]. */
free_area_init(zones_size);
/* Initialize the kernel's ZERO_PGE. */
memset((void *)ZERO_PGE, 0, PAGE_SIZE);
}
#endif /* CONFIG_DISCONTIGMEM */
#if defined(CONFIG_ALPHA_GENERIC) || defined(CONFIG_ALPHA_SRM)
void
srm_paging_stop (void)
{
/* Move the vptb back to where the SRM console expects it. */
swapper_pg_dir[1] = swapper_pg_dir[1023];
tbia();
wrvptptr(0x200000000UL);
hwrpb->vptb = 0x200000000UL;
hwrpb_update_checksum(hwrpb);
/* Reload the page tables that the console had in use. */
load_PCB(&original_pcb);
tbia();
}
#endif
#ifndef CONFIG_DISCONTIGMEM
static void __init
printk_memory_info(void)
{
unsigned long codesize, reservedpages, datasize, initsize, tmp;
extern int page_is_ram(unsigned long) __init;
extern char _text, _etext, _data, _edata;
extern char __init_begin, __init_end;
/* printk all informations */
reservedpages = 0;
for (tmp = 0; tmp < max_low_pfn; tmp++)
/*
* Only count reserved RAM pages
*/
if (page_is_ram(tmp) && PageReserved(mem_map+tmp))
reservedpages++;
codesize = (unsigned long) &_etext - (unsigned long) &_text;
datasize = (unsigned long) &_edata - (unsigned long) &_data;
initsize = (unsigned long) &__init_end - (unsigned long) &__init_begin;
printk("Memory: %luk/%luk available (%luk kernel code, %luk reserved, %luk data, %luk init)\n",
nr_free_pages() << (PAGE_SHIFT-10),
max_mapnr << (PAGE_SHIFT-10),
codesize >> 10,
reservedpages << (PAGE_SHIFT-10),
datasize >> 10,
initsize >> 10);
}
void __init
mem_init(void)
{
max_mapnr = num_physpages = max_low_pfn;
totalram_pages += free_all_bootmem();
high_memory = (void *) __va(max_low_pfn * PAGE_SIZE);
printk_memory_info();
}
#endif /* CONFIG_DISCONTIGMEM */
void
free_reserved_mem(void *start, void *end)
{
void *__start = start;
for (; __start < end; __start += PAGE_SIZE) {
ClearPageReserved(virt_to_page(__start));
init_page_count(virt_to_page(__start));
free_page((long)__start);
totalram_pages++;
}
}
void
free_initmem(void)
{
extern char __init_begin, __init_end;
free_reserved_mem(&__init_begin, &__init_end);
printk ("Freeing unused kernel memory: %ldk freed\n",
(&__init_end - &__init_begin) >> 10);
}
#ifdef CONFIG_BLK_DEV_INITRD
void
free_initrd_mem(unsigned long start, unsigned long end)
{
free_reserved_mem((void *)start, (void *)end);
printk ("Freeing initrd memory: %ldk freed\n", (end - start) >> 10);
}
#endif
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