From: Chuck Lever chuck.lever@oracle.com
commit e28b4fc652c1830796a4d3e09565f30c20f9a2cf upstream.
I hit this while testing nfsd-5.7 with kernel memory debugging enabled on my server:
Mar 30 13:21:45 klimt kernel: BUG: unable to handle page fault for address: ffff8887e6c279a8 Mar 30 13:21:45 klimt kernel: #PF: supervisor read access in kernel mode Mar 30 13:21:45 klimt kernel: #PF: error_code(0x0000) - not-present page Mar 30 13:21:45 klimt kernel: PGD 3601067 P4D 3601067 PUD 87c519067 PMD 87c3e2067 PTE 800ffff8193d8060 Mar 30 13:21:45 klimt kernel: Oops: 0000 [#1] SMP DEBUG_PAGEALLOC PTI Mar 30 13:21:45 klimt kernel: CPU: 2 PID: 1933 Comm: nfsd Not tainted 5.6.0-rc6-00040-g881e87a3c6f9 #1591 Mar 30 13:21:45 klimt kernel: Hardware name: Supermicro Super Server/X10SRL-F, BIOS 1.0c 09/09/2015 Mar 30 13:21:45 klimt kernel: RIP: 0010:svc_rdma_post_chunk_ctxt+0xab/0x284 [rpcrdma] Mar 30 13:21:45 klimt kernel: Code: c1 83 34 02 00 00 29 d0 85 c0 7e 72 48 8b bb a0 02 00 00 48 8d 54 24 08 4c 89 e6 48 8b 07 48 8b 40 20 e8 5a 5c 2b e1 41 89 c6 <8b> 45 20 89 44 24 04 8b 05 02 e9 01 00 85 c0 7e 33 e9 5e 01 00 00 Mar 30 13:21:45 klimt kernel: RSP: 0018:ffffc90000dfbdd8 EFLAGS: 00010286 Mar 30 13:21:45 klimt kernel: RAX: 0000000000000000 RBX: ffff8887db8db400 RCX: 0000000000000030 Mar 30 13:21:45 klimt kernel: RDX: 0000000000000040 RSI: 0000000000000000 RDI: 0000000000000246 Mar 30 13:21:45 klimt kernel: RBP: ffff8887e6c27988 R08: 0000000000000000 R09: 0000000000000004 Mar 30 13:21:45 klimt kernel: R10: ffffc90000dfbdd8 R11: 00c068ef00000000 R12: ffff8887eb4e4a80 Mar 30 13:21:45 klimt kernel: R13: ffff8887db8db634 R14: 0000000000000000 R15: ffff8887fc931000 Mar 30 13:21:45 klimt kernel: FS: 0000000000000000(0000) GS:ffff88885bd00000(0000) knlGS:0000000000000000 Mar 30 13:21:45 klimt kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 Mar 30 13:21:45 klimt kernel: CR2: ffff8887e6c279a8 CR3: 000000081b72e002 CR4: 00000000001606e0 Mar 30 13:21:45 klimt kernel: Call Trace: Mar 30 13:21:45 klimt kernel: ? svc_rdma_vec_to_sg+0x7f/0x7f [rpcrdma] Mar 30 13:21:45 klimt kernel: svc_rdma_send_write_chunk+0x59/0xce [rpcrdma] Mar 30 13:21:45 klimt kernel: svc_rdma_sendto+0xf9/0x3ae [rpcrdma] Mar 30 13:21:45 klimt kernel: ? nfsd_destroy+0x51/0x51 [nfsd] Mar 30 13:21:45 klimt kernel: svc_send+0x105/0x1e3 [sunrpc] Mar 30 13:21:45 klimt kernel: nfsd+0xf2/0x149 [nfsd] Mar 30 13:21:45 klimt kernel: kthread+0xf6/0xfb Mar 30 13:21:45 klimt kernel: ? kthread_queue_delayed_work+0x74/0x74 Mar 30 13:21:45 klimt kernel: ret_from_fork+0x3a/0x50 Mar 30 13:21:45 klimt kernel: Modules linked in: ocfs2_dlmfs ocfs2_stack_o2cb ocfs2_dlm ocfs2_nodemanager ocfs2_stackglue ib_umad ib_ipoib mlx4_ib sb_edac x86_pkg_temp_thermal iTCO_wdt iTCO_vendor_support coretemp kvm_intel kvm irqbypass crct10dif_pclmul crc32_pclmul ghash_clmulni_intel aesni_intel glue_helper crypto_simd cryptd pcspkr rpcrdma i2c_i801 rdma_ucm lpc_ich mfd_core ib_iser rdma_cm iw_cm ib_cm mei_me raid0 libiscsi mei sg scsi_transport_iscsi ioatdma wmi ipmi_si ipmi_devintf ipmi_msghandler acpi_power_meter nfsd nfs_acl lockd auth_rpcgss grace sunrpc ip_tables xfs libcrc32c mlx4_en sd_mod sr_mod cdrom mlx4_core crc32c_intel igb nvme i2c_algo_bit ahci i2c_core libahci nvme_core dca libata t10_pi qedr dm_mirror dm_region_hash dm_log dm_mod dax qede qed crc8 ib_uverbs ib_core Mar 30 13:21:45 klimt kernel: CR2: ffff8887e6c279a8 Mar 30 13:21:45 klimt kernel: ---[ end trace 87971d2ad3429424 ]---
It's absolutely not safe to use resources pointed to by the @send_wr argument of ib_post_send() _after_ that function returns. Those resources are typically freed by the Send completion handler, which can run before ib_post_send() returns.
Thus the trace points currently around ib_post_send() in the server's RPC/RDMA transport are a hazard, even when they are disabled. Rearrange them so that they touch the Work Request only _before_ ib_post_send() is invoked.
Fixes: bd2abef33394 ("svcrdma: Trace key RDMA API events") Fixes: 4201c7464753 ("svcrdma: Introduce svc_rdma_send_ctxt") Signed-off-by: Chuck Lever chuck.lever@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- include/trace/events/rpcrdma.h | 50 ++++++++++++++++++++++++---------- net/sunrpc/xprtrdma/svc_rdma_rw.c | 3 -- net/sunrpc/xprtrdma/svc_rdma_sendto.c | 16 ++++++---- 3 files changed, 46 insertions(+), 23 deletions(-)
--- a/include/trace/events/rpcrdma.h +++ b/include/trace/events/rpcrdma.h @@ -1638,17 +1638,15 @@ DECLARE_EVENT_CLASS(svcrdma_sendcomp_eve
TRACE_EVENT(svcrdma_post_send, TP_PROTO( - const struct ib_send_wr *wr, - int status + const struct ib_send_wr *wr ),
- TP_ARGS(wr, status), + TP_ARGS(wr),
TP_STRUCT__entry( __field(const void *, cqe) __field(unsigned int, num_sge) __field(u32, inv_rkey) - __field(int, status) ),
TP_fast_assign( @@ -1656,12 +1654,11 @@ TRACE_EVENT(svcrdma_post_send, __entry->num_sge = wr->num_sge; __entry->inv_rkey = (wr->opcode == IB_WR_SEND_WITH_INV) ? wr->ex.invalidate_rkey : 0; - __entry->status = status; ),
- TP_printk("cqe=%p num_sge=%u inv_rkey=0x%08x status=%d", + TP_printk("cqe=%p num_sge=%u inv_rkey=0x%08x", __entry->cqe, __entry->num_sge, - __entry->inv_rkey, __entry->status + __entry->inv_rkey ) );
@@ -1726,26 +1723,23 @@ TRACE_EVENT(svcrdma_wc_receive, TRACE_EVENT(svcrdma_post_rw, TP_PROTO( const void *cqe, - int sqecount, - int status + int sqecount ),
- TP_ARGS(cqe, sqecount, status), + TP_ARGS(cqe, sqecount),
TP_STRUCT__entry( __field(const void *, cqe) __field(int, sqecount) - __field(int, status) ),
TP_fast_assign( __entry->cqe = cqe; __entry->sqecount = sqecount; - __entry->status = status; ),
- TP_printk("cqe=%p sqecount=%d status=%d", - __entry->cqe, __entry->sqecount, __entry->status + TP_printk("cqe=%p sqecount=%d", + __entry->cqe, __entry->sqecount ) );
@@ -1841,6 +1835,34 @@ DECLARE_EVENT_CLASS(svcrdma_sendqueue_ev DEFINE_SQ_EVENT(full); DEFINE_SQ_EVENT(retry);
+TRACE_EVENT(svcrdma_sq_post_err, + TP_PROTO( + const struct svcxprt_rdma *rdma, + int status + ), + + TP_ARGS(rdma, status), + + TP_STRUCT__entry( + __field(int, avail) + __field(int, depth) + __field(int, status) + __string(addr, rdma->sc_xprt.xpt_remotebuf) + ), + + TP_fast_assign( + __entry->avail = atomic_read(&rdma->sc_sq_avail); + __entry->depth = rdma->sc_sq_depth; + __entry->status = status; + __assign_str(addr, rdma->sc_xprt.xpt_remotebuf); + ), + + TP_printk("addr=%s sc_sq_avail=%d/%d status=%d", + __get_str(addr), __entry->avail, __entry->depth, + __entry->status + ) +); + #endif /* _TRACE_RPCRDMA_H */
#include <trace/define_trace.h> --- a/net/sunrpc/xprtrdma/svc_rdma_rw.c +++ b/net/sunrpc/xprtrdma/svc_rdma_rw.c @@ -323,8 +323,6 @@ static int svc_rdma_post_chunk_ctxt(stru if (atomic_sub_return(cc->cc_sqecount, &rdma->sc_sq_avail) > 0) { ret = ib_post_send(rdma->sc_qp, first_wr, &bad_wr); - trace_svcrdma_post_rw(&cc->cc_cqe, - cc->cc_sqecount, ret); if (ret) break; return 0; @@ -337,6 +335,7 @@ static int svc_rdma_post_chunk_ctxt(stru trace_svcrdma_sq_retry(rdma); } while (1);
+ trace_svcrdma_sq_post_err(rdma, ret); set_bit(XPT_CLOSE, &xprt->xpt_flags);
/* If even one was posted, there will be a completion. */ --- a/net/sunrpc/xprtrdma/svc_rdma_sendto.c +++ b/net/sunrpc/xprtrdma/svc_rdma_sendto.c @@ -306,15 +306,17 @@ int svc_rdma_send(struct svcxprt_rdma *r }
svc_xprt_get(&rdma->sc_xprt); + trace_svcrdma_post_send(wr); ret = ib_post_send(rdma->sc_qp, wr, NULL); - trace_svcrdma_post_send(wr, ret); - if (ret) { - set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags); - svc_xprt_put(&rdma->sc_xprt); - wake_up(&rdma->sc_send_wait); - } - break; + if (ret) + break; + return 0; } + + trace_svcrdma_sq_post_err(rdma, ret); + set_bit(XPT_CLOSE, &rdma->sc_xprt.xpt_flags); + svc_xprt_put(&rdma->sc_xprt); + wake_up(&rdma->sc_send_wait); return ret; }