Messages in this thread Patch in this message | | | Date | Sat, 31 May 2014 13:33:13 -0700 (PDT) | From | Hugh Dickins <> | Subject | Re: sleeping function warning from __put_anon_vma |
| |
On Thu, 29 May 2014, Dave Jones wrote:
> BUG: sleeping function called from invalid context at kernel/locking/rwsem.c:47 > in_atomic(): 0, irqs_disabled(): 0, pid: 5787, name: trinity-c27 > Preemption disabled at:[<ffffffff990acc7e>] vtime_account_system+0x1e/0x50 > CPU: 0 PID: 5787 Comm: trinity-c27 Not tainted 3.15.0-rc7+ #219 > ffffffff99a47203 0000000099b50bef ffff880239f138c8 ffffffff99739dfb > 0000000000000000 ffff880239f138f0 ffffffff990a026c ffff8801078b5458 > ffff8801078b5450 ffffea00044be980 ffff880239f13908 ffffffff99741c30 > Call Trace: > [<ffffffff99739dfb>] dump_stack+0x4e/0x7a > [<ffffffff990a026c>] __might_sleep+0x11c/0x1b0 > [<ffffffff99741c30>] down_write+0x20/0x40 > [<ffffffff9919337d>] __put_anon_vma+0x3d/0xc0 > [<ffffffff99193998>] page_get_anon_vma+0x68/0xb0 > [<ffffffff991b97e9>] migrate_pages+0x449/0x880 > [<ffffffff9917dc00>] ? isolate_freepages_block+0x360/0x360 > [<ffffffff9917ec8a>] compact_zone+0x38a/0x580 > [<ffffffff9917ef29>] compact_zone_order+0xa9/0x130 > [<ffffffff9917f329>] try_to_compact_pages+0xe9/0x140 > [<ffffffff991616da>] __alloc_pages_direct_compact+0x7a/0x250 > [<ffffffff99161fbb>] __alloc_pages_nodemask+0x70b/0xbb0 > [<ffffffff991a9c3f>] alloc_pages_vma+0xaf/0x1c0 > [<ffffffff991bdc8d>] do_huge_pmd_anonymous_page+0xed/0x3d0 > [<ffffffff991871b4>] handle_mm_fault+0x1b4/0xc50 > [<ffffffff9974358d>] ? retint_restore_args+0xe/0xe > [<ffffffff99746939>] __do_page_fault+0x1c9/0x630 > [<ffffffff99118acb>] ? __acct_update_integrals+0x8b/0x120 > [<ffffffff9974725b>] ? preempt_count_sub+0xab/0x100 > [<ffffffff99746dbe>] do_page_fault+0x1e/0x70 > [<ffffffff997437f2>] page_fault+0x22/0x30
Well caught again. This one doesn't seem to have been plaguing users, but nice to find and fix it. I don't think there are any gotchas to the patch below (in each case we've done a good atomic_inc_not_zero, so the anon_vma cannot be surprisingly freed when we rcu_read_unlock). But even so, I don't think it should go into a tree without Ack from Peter - in looking back there, he might notice something else has changed, or be inspired to fix it in a more satisfying way.
Hugh
[PATCH] mm: fix sleeping function warning from __put_anon_vma
Trinity reports BUG: sleeping function called from invalid context at kernel/locking/rwsem.c:47 in_atomic(): 0, irqs_disabled(): 0, pid: 5787, name: trinity-c27 __might_sleep < down_write < __put_anon_vma < page_get_anon_vma < migrate_pages < compact_zone < compact_zone_order < try_to_compact_pages ..
Right, since conversion to mutex then rwsem, we should not put_anon_vma() from inside an rcu_read_lock()ed section: fix the two places that did so.
Fixes: 88c22088bf23 ("mm: optimize page_lock_anon_vma() fast-path") Reported-by: Dave Jones <davej@redhat.com> Signed-off-by: Hugh Dickins <hughd@google.com> Needs-Ack-from: Peter Zijlstra <peterz@infradead.org> ---
mm/rmap.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
--- 3.15-rc7/mm/rmap.c 2014-04-13 17:24:36.680507189 -0700 +++ linux/mm/rmap.c 2014-05-31 12:02:08.496088637 -0700 @@ -426,12 +426,14 @@ struct anon_vma *page_get_anon_vma(struc * above cannot corrupt). */ if (!page_mapped(page)) { + rcu_read_unlock(); put_anon_vma(anon_vma); anon_vma = NULL; + goto outer; } out: rcu_read_unlock(); - +outer: return anon_vma; } @@ -477,9 +479,10 @@ struct anon_vma *page_lock_anon_vma_read } if (!page_mapped(page)) { + rcu_read_unlock(); put_anon_vma(anon_vma); anon_vma = NULL; - goto out; + goto outer; } /* we pinned the anon_vma, its safe to sleep */ @@ -501,6 +504,7 @@ struct anon_vma *page_lock_anon_vma_read out: rcu_read_unlock(); +outer: return anon_vma; }
| |