diff options
| author | Carsten Otte <cotte@de.ibm.com> | 2011-10-30 15:17:00 +0100 |
|---|---|---|
| committer | Martin Schwidefsky <schwidefsky@de.ibm.com> | 2011-10-30 15:16:44 +0100 |
| commit | a9162f238a84ee05b09ea4b0ebd97fb20448c28c (patch) | |
| tree | 06364148f57e6833bf7c7e66fa69181e141792ba /arch/s390 | |
| parent | [S390] load user asce on sie_fault (diff) | |
| download | linux-a9162f238a84ee05b09ea4b0ebd97fb20448c28c.tar.xz linux-a9162f238a84ee05b09ea4b0ebd97fb20448c28c.zip | |
[S390] fix possible deadlock in gmap_map_segment
Fix possible deadlock reported by lockdep:
qemu-system-s39/2963 is trying to acquire lock:
(&mm->mmap_sem){++++++}, at: gmap_alloc_table+0x9c/0x120
but task is already holding lock:
(&mm->mmap_sem){++++++}, at: gmap_map_segment+0xa6/0x27c
Actually gmap_alloc_table is the only called in gmap_map_segment with
mmap_sem held, thus it's safe to simply remove the inner lock.
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Diffstat (limited to 'arch/s390')
| -rw-r--r-- | arch/s390/mm/pgtable.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c index 529a08838376..e4a4cefb92b3 100644 --- a/arch/s390/mm/pgtable.c +++ b/arch/s390/mm/pgtable.c @@ -256,6 +256,9 @@ void gmap_disable(struct gmap *gmap) } EXPORT_SYMBOL_GPL(gmap_disable); +/* + * gmap_alloc_table is assumed to be called with mmap_sem held + */ static int gmap_alloc_table(struct gmap *gmap, unsigned long *table, unsigned long init) { @@ -267,14 +270,12 @@ static int gmap_alloc_table(struct gmap *gmap, return -ENOMEM; new = (unsigned long *) page_to_phys(page); crst_table_init(new, init); - down_read(&gmap->mm->mmap_sem); if (*table & _REGION_ENTRY_INV) { list_add(&page->lru, &gmap->crst_list); *table = (unsigned long) new | _REGION_ENTRY_LENGTH | (*table & _REGION_ENTRY_TYPE_MASK); } else __free_pages(page, ALLOC_ORDER); - up_read(&gmap->mm->mmap_sem); return 0; } |