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| author | David Howells <dhowells@redhat.com> | 2007-03-22 00:11:24 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-03-22 19:39:06 -0700 |
| commit | 165b239270be610a1e3999cb0d2e4e2c1f2a8fd4 (patch) | |
| tree | 3ae32cc616047b3960d1fe33b0583faa3094b82c /mm/nommu.c | |
| parent | d56e03cd275486eb8141116a7af2df7457cb0115 (diff) | |
| download | linux-165b239270be610a1e3999cb0d2e4e2c1f2a8fd4.tar.gz | |
[PATCH] NOMMU: make SYSV SHM nattch work correctly
Make the SYSV SHM nattch counter work correctly by forcing multiple VMAs to be produced to represent MAP_SHARED segments, even if they overlap exactly. Using this test program: http://people.redhat.com/~dhowells/doshm.c Run as: doshm sysv I can see nattch going from one before the patch: # /doshm sysv Command: sysv shmid: 65536 memory: 0xc3700000 c0b00000-c0b04000 rw-p 00000000 00:00 0 c0bb0000-c0bba788 r-xs 00000000 00:0b 14582157 /lib/ld-uClibc-0.9.28.so c3180000-c31dede4 r-xs 00000000 00:0b 14582179 /lib/libuClibc-0.9.28.so c3520000-c352278c rw-p 00000000 00:0b 13763417 /doshm c3584000-c35865e8 r-xs 00000000 00:0b 13763417 /doshm c3588000-c358aa00 rw-p 00008000 00:0b 14582157 /lib/ld-uClibc-0.9.28.so c3590000-c359b6c0 rw-p 00000000 00:00 0 c3620000-c3640000 rwxp 00000000 00:00 0 c3700000-c37fa000 rw-S 00000000 00:06 1411 /SYSV00000000 (deleted) c3700000-c37fa000 rw-S 00000000 00:06 1411 /SYSV00000000 (deleted) nattch 1 To two after the patch: # /doshm sysv Command: sysv shmid: 0 memory: 0xc3700000 c0bb0000-c0bba788 r-xs 00000000 00:0b 14582157 /lib/ld-uClibc-0.9.28.so c3180000-c31dede4 r-xs 00000000 00:0b 14582179 /lib/libuClibc-0.9.28.so c3320000-c3340000 rwxp 00000000 00:00 0 c3530000-c35325e8 r-xs 00000000 00:0b 13763417 /doshm c3534000-c353678c rw-p 00000000 00:0b 13763417 /doshm c3538000-c353aa00 rw-p 00008000 00:0b 14582157 /lib/ld-uClibc-0.9.28.so c3590000-c359b6c0 rw-p 00000000 00:00 0 c35a4000-c35a8000 rw-p 00000000 00:00 0 c3700000-c37fa000 rw-S 00000000 00:06 1369 /SYSV00000000 (deleted) c3700000-c37fa000 rw-S 00000000 00:06 1369 /SYSV00000000 (deleted) nattch 2 That's +1 to nattch for each shmat() made. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/nommu.c')
| -rw-r--r-- | mm/nommu.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/mm/nommu.c b/mm/nommu.c index ba6df4d29979..cbbc13774819 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -826,6 +826,11 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long pglen = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; unsigned long vmpglen; + /* suppress VMA sharing for shared regions */ + if (vm_flags & VM_SHARED && + capabilities & BDI_CAP_MAP_DIRECT) + goto dont_share_VMAs; + for (rb = rb_first(&nommu_vma_tree); rb; rb = rb_next(rb)) { vma = rb_entry(rb, struct vm_area_struct, vm_rb); @@ -859,6 +864,7 @@ unsigned long do_mmap_pgoff(struct file *file, goto shared; } + dont_share_VMAs: vma = NULL; /* obtain the address at which to make a shared mapping |