On Fri, Dec 6, 2019 at 9:51 AM Dongsheng Yang <dongsheng.yang@easystack.cn> wrote:
在 12/6/2019 9:46 PM, Jason Dillaman 写道:
On Fri, Dec 6, 2019 at 12:12 AM Dongsheng Yang <dongsheng.yang@easystack.cn> wrote:
On 12/06/2019 12:50 PM, yangjun@cmss.chinamobile.com wrote:
Hi Jason, dongsheng I found a problem using rbd_open_by_id when connection timeout(errno = 110, ceph version 12.2.8, there is no change about rbd_open_by_id in master branch). int r = ictx->state->open(false); if (r < 0) { // r = -110 delete ictx; // crash，the stack is shown below： } else { *image = (rbd_image_t)ictx; } Stack is ： (gdb) bt Program terminated with signal 11, Segmentation fault. #0 Mutex::Lock (this=this@entry=0x8, no_lockdep=no_lockdep@entry=false) at /var/lib/jenkins/workspace/ceph_L/ceph/src/common/Mutex.cc:92 #1 0x0000ffff765eb814 in Locker (m=..., this=<synthetic pointer>) at /var/lib/jenkins/workspace/ceph_L/ceph/src/common/Mutex.h:115 #2 PerfCountersCollection::remove (this=0x0, l=0xffff85bf0588 <main_arena+88>) at /var/lib/jenkins/workspace/ceph_L/ceph/src/common/perf_counters.cc:62 #3 0x0000ffff757f26c4 in librbd::ImageCtx::perf_stop (this=0x2065d2f0) at /var/lib/jenkins/workspace/ceph_L/ceph/src/librbd/ImageCtx.cc:426 #4 0x0000ffff757f6e48 in librbd::ImageCtx::~ImageCtx (this=0x2065d2f0, __in_chrg=<optimized out>) at /var/lib/jenkins/workspace/ceph_L/ceph/src/librbd/ImageCtx.cc:239 #5 0x0000ffff757e8e70 in rbd_open_by_id (p=p@entry=0x2065e780, id=id@entry=0xffff85928bb4 "20376aa706c0", image=image@entry=0xffff75b9b0b8, snap_name=snap_name@entry=0x0) at /var/lib/jenkins/workspace/ceph_L/ceph/src/librbd/librbd.cc:2692 #6 0x0000ffff75aed524 in __pyx_pf_3rbd_5Image___init__ ( __pyx_v_read_only=0xffff85f02bb8 <_Py_ZeroStruct>, __pyx_v_snapshot=0xffff85f15938 <_Py_NoneStruct>, __pyx_v_by_id=0xffff85f02ba0 <_Py_TrueStruct>, __pyx_v_name=0xffff85928b90, __pyx_v_ioctx=0xffff7f0283d0, __pyx_v_self=0xffff75b9b0a8) at /var/lib/jenkins/workspace/ceph_L/ceph/build/src/pybind/rbd/pyrex/rbd.c:12662 #7 __pyx_pw_3rbd_5Image_1__init__ (__pyx_v_self=0xffff75b9b0a8, __pyx_args=<optimized out>, __pyx_kwds=<optimized out>) at /var/lib/jenkins/workspace/ceph_L/ceph/build/src/pybind/rbd/pyrex/rbd.c:12378 #8 0x0000ffff85e02924 in type_call () from /lib64/libpython2.7.so.1.0 #9 0x0000ffff85dac254 in PyObject_Call () from /lib64/libpython2.7.so.1.0
I suspect you will hit tons of errors and corruption and leaking RADOS objects when you start injecting RADOS timeouts. It's not something librbd really supports or tests against -- so you need to expect the unexpected. Definitely feel free to open a PR to fix it, though -- but otherwise it would be a really *low* priority to fix.
Meanwhile, I have sone questions about rbd_open, if state->open failed（return value r < 0）, Is there a risk of memory leaks about ictx? extern "C" int rbd_open(rados_ioctx_t p, const char *name, rbd_image_t *image, const char *snap_name) { librados::IoCtx io_ctx; librados::IoCtx::from_rados_ioctx_t(p, io_ctx); TracepointProvider::initialize<tracepoint_traits>(get_cct(io_ctx)); librbd::ImageCtx *ictx = new librbd::ImageCtx(name, "", snap_name, io_ctx, false); tracepoint(librbd, open_image_enter, ictx, ictx->name.c_str(), ictx->id.c_str(), ictx->snap_name.c_str(), ictx->read_only);
int r = ictx->state->open(false); if (r >= 0) { // if r < 0, Is there a risk of memory leaks?
Good catch. I think there is. And same at rbd_open_read_only. Seems we need a patch to fix them. No, that's not a memory leak. The blocking version of "ImageState::open" will free the "ImageCtx" memory upon failure.
My bad, I did not look it carefully before repling this mail,
I realized that we delete ctx in rbd_open_by_id but not in rbd_open, so I thought it's a memory leak
in rbd_open. But I was wrong as you mentioned, it is released in state->open(). So we dont need to add
a delete in rbd_open(), on the contrary, we need to remove the "delete ictx" to avoid double-free problem as below:
diff --git a/src/librbd/librbd.cc b/src/librbd/librbd.cc index 6c303c9..b518fad 100644 --- a/src/librbd/librbd.cc +++ b/src/librbd/librbd.cc @@ -3924,9 +3924,7 @@ extern "C" int rbd_open_by_id(rados_ioctx_t p, const char *id, ictx->id.c_str(), ictx->snap_name.c_str(), ictx->read_only);
int r = ictx->state->open(0); - if (r < 0) { - delete ictx; - } else { + if (r >= 0) { *image = (rbd_image_t)ictx; } tracepoint(librbd, open_image_exit, r); @@ -3999,9 +3997,7 @@ extern "C" int rbd_open_by_id_read_only(rados_ioctx_t p, const char *id, ictx->id.c_str(), ictx->snap_name.c_str(), ictx->read_only);
int r = ictx->state->open(0); - if (r < 0) { - delete ictx; - } else { + if (r >= 0) { *image = (rbd_image_t)ictx; }
tracepoint(librbd, open_image_exit, r);
There is a reproduce test.c attached.
Opened https://tracker.ceph.com/issues/43178
Thanx
Yang
Thanx Yang
*image = (rbd_image_t)ictx; } tracepoint(librbd, open_image_exit, r); return r; }
Can you give me some advice? many thanks.
________________________________ yangjun@cmss.chinamobile.com
Thanks, -- Jason