From e26a51148f3ebd859bca8bf2e0f212839b447f62 Mon Sep 17 00:00:00 2001 From: KOSAKI Motohiro Date: Wed, 28 Dec 2011 15:57:11 -0800 Subject: 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 #include #include #include #include #include #include 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 Acked-by: Johannes Weiner Cc: Minchan Kim Cc: Caspar Zhang Cc: KOSAKI Motohiro Cc: Christoph Lameter Cc: Hugh Dickins Cc: Mel Gorman Cc: Lee Schermerhorn Cc: [3.1.x] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/mempolicy.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/mempolicy.c b/mm/mempolicy.c index adc395481813..c3fdbcb17658 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; -- cgit v1.2.3-58-ga151