| commit | 4879e0dfe9c9199e55566a6025a729854bb2a00e | |
| author | Hugh Dickins <hugh@veritas.com> | |
| Thu, 3 May 2007 22:54:25 +0000 (4 00:54 +0200) | ||
| committer | Adrian Bunk <bunk@stusta.de> | |
| Thu, 3 May 2007 22:54:25 +0000 (4 00:54 +0200) | ||
| tree | dae9fb7549555e94c71d41701f67875b04557035 | treesnapshot (tar.gz zip) |
| parent | 7943951f236f91699a634097a70abc35927efeb9 | commitdiff |
holepunch: fix mmap_sem i_mutex deadlock
sys_madvise has down_write of mmap_sem, then madvise_remove calls
vmtruncate_range which takes i_mutex and i_alloc_sem: no, we can
easily devise deadlocks from that ordering.
madvise_remove drop mmap_sem while calling vmtruncate_range: luckily,
since madvise_remove doesn't split or merge vmas, it's easy to handle
this case with a NULL prev, without restructuring sys_madvise. (Though
sad to retake mmap_sem when it's unlikely to be needed, and certainly
down_read is sufficient for MADV_REMOVE, unlike the other madvices.)
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
sys_madvise has down_write of mmap_sem, then madvise_remove calls
vmtruncate_range which takes i_mutex and i_alloc_sem: no, we can
easily devise deadlocks from that ordering.
madvise_remove drop mmap_sem while calling vmtruncate_range: luckily,
since madvise_remove doesn't split or merge vmas, it's easy to handle
this case with a NULL prev, without restructuring sys_madvise. (Though
sad to retake mmap_sem when it's unlikely to be needed, and certainly
down_read is sufficient for MADV_REMOVE, unlike the other madvices.)
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
| mm/madvise.c | diffblobblamehistory |