https://github.com/torvalds/linux
Revision 3ad33b2436b545cbe8b28e53f3710432cad457ab authored by Lee Schermerhorn on 15 November 2007, 00:59:10 UTC, committed by Linus Torvalds on 15 November 2007, 02:45:38 UTC
We hit the BUG_ON() in mm/rmap.c:vma_address() when trying to migrate via mbind(MPOL_MF_MOVE) a non-anon region that spans multiple vmas. For anon-regions, we just fail to migrate any pages beyond the 1st vma in the range. This occurs because do_mbind() collects a list of pages to migrate by calling check_range(). check_range() walks the task's mm, spanning vmas as necessary, to collect the migratable pages into a list. Then, do_mbind() calls migrate_pages() passing the list of pages, a function to allocate new pages based on vma policy [new_vma_page()], and a pointer to the first vma of the range. For each page in the list, new_vma_page() calls page_address_in_vma() passing the page and the vma [first in range] to obtain the address to get for alloc_page_vma(). The page address is needed to get interleaving policy correct. If the pages in the list come from multiple vmas, eventually, new_page_address() will pass that page to page_address_in_vma() with the incorrect vma. For !PageAnon pages, this will result in a bug check in rmap.c:vma_address(). For anon pages, vma_address() will just return EFAULT and fail the migration. This patch modifies new_vma_page() to check the return value from page_address_in_vma(). If the return value is EFAULT, new_vma_page() searchs forward via vm_next for the vma that maps the page--i.e., that does not return EFAULT. This assumes that the pages in the list handed to migrate_pages() is in address order. This is currently case. The patch documents this assumption in a new comment block for new_vma_page(). If new_vma_page() cannot locate the vma mapping the page in a forward search in the mm, it will pass a NULL vma to alloc_page_vma(). This will result in the allocation using the task policy, if any, else system default policy. This situation is unlikely, but the patch documents this behavior with a comment. Note, this patch results in restarting from the first vma in a multi-vma range each time new_vma_page() is called. If this is not acceptable, we can make the vma argument a pointer, both in new_vma_page() and it's caller unmap_and_move() so that the value held by the loop in migrate_pages() always passes down the last vma in which a page was found. This will require changes to all new_page_t functions passed to migrate_pages(). Is this necessary? For this patch to work, we can't bug check in vma_address() for pages outside the argument vma. This patch removes the BUG_ON(). All other callers [besides new_vma_page()] already check the return status. Tested on x86_64, 4 node NUMA platform. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 parent e1a1c99
Tip revision: 3ad33b2436b545cbe8b28e53f3710432cad457ab authored by Lee Schermerhorn on 15 November 2007, 00:59:10 UTC
Migration: find correct vma in new_vma_page()
Migration: find correct vma in new_vma_page()
Tip revision: 3ad33b2
bloat-o-meter
#!/usr/bin/python
#
# Copyright 2004 Matt Mackall <mpm@selenic.com>
#
# inspired by perl Bloat-O-Meter (c) 1997 by Andi Kleen
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.
import sys, os, re
if len(sys.argv) != 3:
sys.stderr.write("usage: %s file1 file2\n" % sys.argv[0])
sys.exit(-1)
def getsizes(file):
sym = {}
for l in os.popen("nm --size-sort " + file).readlines():
size, type, name = l[:-1].split()
if type in "tTdDbB":
if "." in name: name = "static." + name.split(".")[0]
sym[name] = sym.get(name, 0) + int(size, 16)
return sym
old = getsizes(sys.argv[1])
new = getsizes(sys.argv[2])
grow, shrink, add, remove, up, down = 0, 0, 0, 0, 0, 0
delta, common = [], {}
for a in old:
if a in new:
common[a] = 1
for name in old:
if name not in common:
remove += 1
down += old[name]
delta.append((-old[name], name))
for name in new:
if name not in common:
add += 1
up += new[name]
delta.append((new[name], name))
for name in common:
d = new.get(name, 0) - old.get(name, 0)
if d>0: grow, up = grow+1, up+d
if d<0: shrink, down = shrink+1, down-d
delta.append((d, name))
delta.sort()
delta.reverse()
print "add/remove: %s/%s grow/shrink: %s/%s up/down: %s/%s (%s)" % \
(add, remove, grow, shrink, up, -down, up-down)
print "%-40s %7s %7s %+7s" % ("function", "old", "new", "delta")
for d, n in delta:
if d: print "%-40s %7s %7s %+7d" % (n, old.get(n,"-"), new.get(n,"-"), d)
Computing file changes ...
