From 9d8cebd4bcd7c3878462fdfda34bbcdeb4df7ef4 Mon Sep 17 00:00:00 2001 From: KOSAKI Motohiro Date: Fri, 5 Mar 2010 13:41:57 -0800 Subject: [PATCH] mm: fix mbind vma merge problem Strangely, current mbind() doesn't merge vma with neighbor vma although it's possible. Unfortunately, many vma can reduce performance... This patch fixes it. reproduced program ---------------------------------------------------------------- #include #include #include #include #include #include #include static unsigned long pagesize; int main(int argc, char** argv) { void* addr; int ch; int node; struct bitmask *nmask = numa_allocate_nodemask(); int err; int node_set = 0; char buf[128]; while ((ch = getopt(argc, argv, "n:")) != -1){ switch (ch){ case 'n': node = strtol(optarg, NULL, 0); numa_bitmask_setbit(nmask, node); node_set = 1; break; default: ; } } argc -= optind; argv += optind; if (!node_set) numa_bitmask_setbit(nmask, 0); pagesize = getpagesize(); addr = mmap(NULL, pagesize*3, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE, 0, 0); if (addr == MAP_FAILED) perror("mmap "), exit(1); fprintf(stderr, "pid = %d \n" "addr = %p\n", getpid(), addr); /* make page populate */ memset(addr, 0, pagesize*3); /* first mbind */ err = mbind(addr+pagesize, pagesize, MPOL_BIND, nmask->maskp, nmask->size, MPOL_MF_MOVE_ALL); if (err) error("mbind1 "); /* second mbind */ err = mbind(addr, pagesize*3, MPOL_DEFAULT, NULL, 0, 0); if (err) error("mbind2 "); sprintf(buf, "cat /proc/%d/maps", getpid()); system(buf); return 0; } ---------------------------------------------------------------- result without this patch addr = 0x7fe26ef09000 [snip] 7fe26ef09000-7fe26ef0a000 rw-p 00000000 00:00 0 7fe26ef0a000-7fe26ef0b000 rw-p 00000000 00:00 0 7fe26ef0b000-7fe26ef0c000 rw-p 00000000 00:00 0 7fe26ef0c000-7fe26ef0d000 rw-p 00000000 00:00 0 => 0x7fe26ef09000-0x7fe26ef0c000 have three vmas. result with this patch addr = 0x7fc9ebc76000 [snip] 7fc9ebc76000-7fc9ebc7a000 rw-p 00000000 00:00 0 7fffbe690000-7fffbe6a5000 rw-p 00000000 00:00 0 [stack] => 0x7fc9ebc76000-0x7fc9ebc7a000 have only one vma. [minchan.kim@gmail.com: fix file offset passed to vma_merge()] Signed-off-by: KOSAKI Motohiro Reviewed-by: Christoph Lameter Cc: Nick Piggin Cc: Hugh Dickins Cc: Andrea Arcangeli Cc: Mel Gorman Cc: Lee Schermerhorn Signed-off-by: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/mempolicy.c | 52 +++++++++++++++++++++++++++++++++++++------------- 1 file changed, 39 insertions(+), 13 deletions(-) diff --git a/mm/mempolicy.c b/mm/mempolicy.c index 290fb5bf0440..44dd9d1521ec 100644 --- a/mm/mempolicy.c +++ b/mm/mempolicy.c @@ -563,24 +563,50 @@ static int policy_vma(struct vm_area_struct *vma, struct mempolicy *new) } /* Step 2: apply policy to a range and do splits. */ -static int mbind_range(struct vm_area_struct *vma, unsigned long start, - unsigned long end, struct mempolicy *new) +static int mbind_range(struct mm_struct *mm, unsigned long start, + unsigned long end, struct mempolicy *new_pol) { struct vm_area_struct *next; - int err; + struct vm_area_struct *prev; + struct vm_area_struct *vma; + int err = 0; + pgoff_t pgoff; + unsigned long vmstart; + unsigned long vmend; - err = 0; - for (; vma && vma->vm_start < end; vma = next) { + vma = find_vma_prev(mm, start, &prev); + if (!vma || vma->vm_start > start) + return -EFAULT; + + for (; vma && vma->vm_start < end; prev = vma, vma = next) { next = vma->vm_next; - if (vma->vm_start < start) - err = split_vma(vma->vm_mm, vma, start, 1); - if (!err && vma->vm_end > end) - err = split_vma(vma->vm_mm, vma, end, 0); - if (!err) - err = policy_vma(vma, new); + vmstart = max(start, vma->vm_start); + vmend = min(end, vma->vm_end); + + pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); + prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags, + vma->anon_vma, vma->vm_file, pgoff, new_pol); + if (prev) { + vma = prev; + next = vma->vm_next; + continue; + } + if (vma->vm_start != vmstart) { + err = split_vma(vma->vm_mm, vma, vmstart, 1); + if (err) + goto out; + } + if (vma->vm_end != vmend) { + err = split_vma(vma->vm_mm, vma, vmend, 0); + if (err) + goto out; + } + err = policy_vma(vma, new_pol); if (err) - break; + goto out; } + + out: return err; } @@ -1047,7 +1073,7 @@ static long do_mbind(unsigned long start, unsigned long len, if (!IS_ERR(vma)) { int nr_failed = 0; - err = mbind_range(vma, start, end, new); + err = mbind_range(mm, start, end, new); if (!list_empty(&pagelist)) nr_failed = migrate_pages(&pagelist, new_vma_page, -- 2.20.1