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authorKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>2011-12-28 15:57:11 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2011-12-29 16:31:57 -0800
commite26a51148f3ebd859bca8bf2e0f212839b447f62 (patch)
treeaa3a328dabee8a9f1dccc8c8178f690d0eacbf1e
parent757e55c23dc62eb5adf45368a72f6b26d6a71ae5 (diff)
downloadlinux-linaro-e26a51148f3ebd859bca8bf2e0f212839b447f62.tar.gz
mm/mempolicy.c: refix mbind_range() vma issue
commit 8aacc9f550 ("mm/mempolicy.c: fix pgoff in mbind vma merge") is the slightly incorrect fix. Why? Think following case. 1. map 4 pages of a file at offset 0 [0123] 2. map 2 pages just after the first mapping of the same file but with page offset 2 [0123][23] 3. mbind() 2 pages from the first mapping at offset 2. mbind_range() should treat new vma is, [0123][23] |23| mbind vma but it does [0123][23] |01| mbind vma Oops. then, it makes wrong vma merge and splitting ([01][0123] or similar). This patch fixes it. [testcase] test result - before the patch case4: 126: test failed. expect '2,4', actual '2,2,2' case5: passed case6: passed case7: passed case8: passed case_n: 246: test failed. expect '4,2', actual '1,4' ------------[ cut here ]------------ kernel BUG at mm/filemap.c:135! invalid opcode: 0000 [#4] SMP DEBUG_PAGEALLOC (snip long bug on messages) test result - after the patch case4: passed case5: passed case6: passed case7: passed case8: passed case_n: passed source: mbind_vma_test.c ============================================================ #include <numaif.h> #include <numa.h> #include <sys/mman.h> #include <stdio.h> #include <unistd.h> #include <stdlib.h> #include <string.h> static unsigned long pagesize; void* mmap_addr; struct bitmask *nmask; char buf[1024]; FILE *file; char retbuf[10240] = ""; int mapped_fd; char *rubysrc = "ruby -e '\ pid = %d; \ vstart = 0x%llx; \ vend = 0x%llx; \ s = `pmap -q #{pid}`; \ rary = []; \ s.each_line {|line|; \ ary=line.split(\" \"); \ addr = ary[0].to_i(16); \ if(vstart <= addr && addr < vend) then \ rary.push(ary[1].to_i()/4); \ end; \ }; \ print rary.join(\",\"); \ '"; void init(void) { void* addr; char buf[128]; nmask = numa_allocate_nodemask(); numa_bitmask_setbit(nmask, 0); pagesize = getpagesize(); sprintf(buf, "%s", "mbind_vma_XXXXXX"); mapped_fd = mkstemp(buf); if (mapped_fd == -1) perror("mkstemp "), exit(1); unlink(buf); if (lseek(mapped_fd, pagesize*8, SEEK_SET) < 0) perror("lseek "), exit(1); if (write(mapped_fd, "\0", 1) < 0) perror("write "), exit(1); addr = mmap(NULL, pagesize*8, PROT_NONE, MAP_SHARED, mapped_fd, 0); if (addr == MAP_FAILED) perror("mmap "), exit(1); if (mprotect(addr+pagesize, pagesize*6, PROT_READ|PROT_WRITE) < 0) perror("mprotect "), exit(1); mmap_addr = addr + pagesize; /* make page populate */ memset(mmap_addr, 0, pagesize*6); } void fin(void) { void* addr = mmap_addr - pagesize; munmap(addr, pagesize*8); memset(buf, 0, sizeof(buf)); memset(retbuf, 0, sizeof(retbuf)); } void mem_bind(int index, int len) { int err; err = mbind(mmap_addr+pagesize*index, pagesize*len, MPOL_BIND, nmask->maskp, nmask->size, 0); if (err) perror("mbind "), exit(err); } void mem_interleave(int index, int len) { int err; err = mbind(mmap_addr+pagesize*index, pagesize*len, MPOL_INTERLEAVE, nmask->maskp, nmask->size, 0); if (err) perror("mbind "), exit(err); } void mem_unbind(int index, int len) { int err; err = mbind(mmap_addr+pagesize*index, pagesize*len, MPOL_DEFAULT, NULL, 0, 0); if (err) perror("mbind "), exit(err); } void Assert(char *expected, char *value, char *name, int line) { if (strcmp(expected, value) == 0) { fprintf(stderr, "%s: passed\n", name); return; } else { fprintf(stderr, "%s: %d: test failed. expect '%s', actual '%s'\n", name, line, expected, value); // exit(1); } } /* AAAA PPPPPPNNNNNN might become PPNNNNNNNNNN case 4 below */ void case4(void) { init(); sprintf(buf, rubysrc, getpid(), mmap_addr, mmap_addr+pagesize*6); mem_bind(0, 4); mem_unbind(2, 2); file = popen(buf, "r"); fread(retbuf, sizeof(retbuf), 1, file); Assert("2,4", retbuf, "case4", __LINE__); fin(); } /* AAAA PPPPPPNNNNNN might become PPPPPPPPPPNN case 5 below */ void case5(void) { init(); sprintf(buf, rubysrc, getpid(), mmap_addr, mmap_addr+pagesize*6); mem_bind(0, 2); mem_bind(2, 2); file = popen(buf, "r"); fread(retbuf, sizeof(retbuf), 1, file); Assert("4,2", retbuf, "case5", __LINE__); fin(); } /* AAAA PPPPNNNNXXXX might become PPPPPPPPPPPP 6 */ void case6(void) { init(); sprintf(buf, rubysrc, getpid(), mmap_addr, mmap_addr+pagesize*6); mem_bind(0, 2); mem_bind(4, 2); mem_bind(2, 2); file = popen(buf, "r"); fread(retbuf, sizeof(retbuf), 1, file); Assert("6", retbuf, "case6", __LINE__); fin(); } /* AAAA PPPPNNNNXXXX might become PPPPPPPPXXXX 7 */ void case7(void) { init(); sprintf(buf, rubysrc, getpid(), mmap_addr, mmap_addr+pagesize*6); mem_bind(0, 2); mem_interleave(4, 2); mem_bind(2, 2); file = popen(buf, "r"); fread(retbuf, sizeof(retbuf), 1, file); Assert("4,2", retbuf, "case7", __LINE__); fin(); } /* AAAA PPPPNNNNXXXX might become PPPPNNNNNNNN 8 */ void case8(void) { init(); sprintf(buf, rubysrc, getpid(), mmap_addr, mmap_addr+pagesize*6); mem_bind(0, 2); mem_interleave(4, 2); mem_interleave(2, 2); file = popen(buf, "r"); fread(retbuf, sizeof(retbuf), 1, file); Assert("2,4", retbuf, "case8", __LINE__); fin(); } void case_n(void) { init(); sprintf(buf, rubysrc, getpid(), mmap_addr, mmap_addr+pagesize*6); /* make redundunt mappings [0][1234][34][7] */ mmap(mmap_addr + pagesize*4, pagesize*2, PROT_READ|PROT_WRITE, MAP_FIXED|MAP_SHARED, mapped_fd, pagesize*3); /* Expect to do nothing. */ mem_unbind(2, 2); file = popen(buf, "r"); fread(retbuf, sizeof(retbuf), 1, file); Assert("4,2", retbuf, "case_n", __LINE__); fin(); } int main(int argc, char** argv) { case4(); case5(); case6(); case7(); case8(); case_n(); return 0; } ============================================================= Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan.kim@gmail.com> Cc: Caspar Zhang <caspar@casparzhang.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Christoph Lameter <cl@linux.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: <stable@vger.kernel.org> [3.1.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/mempolicy.c11
1 files changed, 10 insertions, 1 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index adc39548181..c3fdbcb1765 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -636,6 +636,7 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
struct vm_area_struct *prev;
struct vm_area_struct *vma;
int err = 0;
+ pgoff_t pgoff;
unsigned long vmstart;
unsigned long vmend;
@@ -643,13 +644,21 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
if (!vma || vma->vm_start > start)
return -EFAULT;
+ if (start > vma->vm_start)
+ prev = vma;
+
for (; vma && vma->vm_start < end; prev = vma, vma = next) {
next = vma->vm_next;
vmstart = max(start, vma->vm_start);
vmend = min(end, vma->vm_end);
+ if (mpol_equal(vma_policy(vma), new_pol))
+ continue;
+
+ pgoff = vma->vm_pgoff +
+ ((vmstart - vma->vm_start) >> PAGE_SHIFT);
prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
- vma->anon_vma, vma->vm_file, vma->vm_pgoff,
+ vma->anon_vma, vma->vm_file, pgoff,
new_pol);
if (prev) {
vma = prev;