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Commit ef93247325028a35e089f3012c270379a89d052c

Authored by Joonsoo Kim
Committed by Linus Torvalds
1 parent 7136851117
Exists in smarc-l5.0.0_1.0.0-ga and in 5 other branches imx_3.10.17_1.0.1_ga, imx_3.10.53_1.1.0_ga, imx_3.14.28_1.0.0_ga, smarc-imx_3.10.53_1.1.0_ga, smarc-imx_3.14.28_1.0.0_ga

mm, vmalloc: change iterating a vmlist to find_vm_area() 

This patchset removes vm_struct list management after initializing
vmalloc.  Adding and removing an entry to vmlist is linear time
complexity, so it is inefficient.  If we maintain this list, overall
time complexity of adding and removing area to vmalloc space is O(N),
although we use rbtree for finding vacant place and it's time complexity
is just O(logN).

And vmlist and vmlist_lock is used many places of outside of vmalloc.c.
It is preferable that we hide this raw data structure and provide
well-defined function for supporting them, because it makes that they
cannot mistake when manipulating theses structure and it makes us easily
maintain vmalloc layer.

For kexec and makedumpfile, I export vmap_area_list, instead of vmlist.
This comes from Atsushi's recommendation.  For more information, please
refer below link.  https://lkml.org/lkml/2012/12/6/184

This patch:

The purpose of iterating a vmlist is finding vm area with specific virtual
address.  find_vm_area() is provided for this purpose and more efficient,
because it uses a rbtree.  So change it.

Signed-off-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Guan Xuetao <gxt@mprc.pku.edu.cn>
Acked-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Chris Metcalf <cmetcalf@tilera.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
Cc: Dave Anderson <anderson@redhat.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Showing 3 changed files with 7 additions and 24 deletions Side-by-side Diff

arch/tile/mm/pgtable.c
Diff comments   View file @ ef93247
... ... @@ -592,12 +592,7 @@
592 592 in parallel. Reuse of the virtual address is prevented by
593 593 leaving it in the global lists until we're done with it.
594 594 cpa takes care of the direct mappings. */
595   - read_lock(&vmlist_lock);
596   - for (p = vmlist; p; p = p->next) {
597   - if (p->addr == addr)
598   - break;
599   - }
600   - read_unlock(&vmlist_lock);
  595 + p = find_vm_area((void *)addr);
601 596  
602 597 if (!p) {
603 598 pr_err("iounmap: bad address %p\n", addr);
arch/unicore32/mm/ioremap.c
Diff comments   View file @ ef93247
... ... @@ -235,7 +235,7 @@
235 235 void __uc32_iounmap(volatile void __iomem *io_addr)
236 236 {
237 237 void *addr = (void *)(PAGE_MASK & (unsigned long)io_addr);
238   - struct vm_struct **p, *tmp;
  238 + struct vm_struct *vm;
239 239  
240 240 /*
241 241 * If this is a section based mapping we need to handle it
... ... @@ -244,17 +244,10 @@
244 244 * all the mappings before the area can be reclaimed
245 245 * by someone else.
246 246 */
247   - write_lock(&vmlist_lock);
248   - for (p = &vmlist ; (tmp = *p) ; p = &tmp->next) {
249   - if ((tmp->flags & VM_IOREMAP) && (tmp->addr == addr)) {
250   - if (tmp->flags & VM_UNICORE_SECTION_MAPPING) {
251   - unmap_area_sections((unsigned long)tmp->addr,
252   - tmp->size);
253   - }
254   - break;
255   - }
256   - }
257   - write_unlock(&vmlist_lock);
  247 + vm = find_vm_area(addr);
  248 + if (vm && (vm->flags & VM_IOREMAP) &&
  249 + (vm->flags & VM_UNICORE_SECTION_MAPPING))
  250 + unmap_area_sections((unsigned long)vm->addr, vm->size);
258 251  
259 252 vunmap(addr);
260 253 }
arch/x86/mm/ioremap.c
Diff comments   View file @ ef93247
... ... @@ -282,12 +282,7 @@
282 282 in parallel. Reuse of the virtual address is prevented by
283 283 leaving it in the global lists until we're done with it.
284 284 cpa takes care of the direct mappings. */
285   - read_lock(&vmlist_lock);
286   - for (p = vmlist; p; p = p->next) {
287   - if (p->addr == (void __force *)addr)
288   - break;
289   - }
290   - read_unlock(&vmlist_lock);
  285 + p = find_vm_area((void __force *)addr);
291 286  
292 287 if (!p) {
293 288 printk(KERN_ERR "iounmap: bad address %p\n", addr);