Hi, I got the following BUG_ON() trace when there is high memory pressure on a system. I'm curious whether it's kind of aggressive to trigger a BUG() when a memory allocation failure is encountered? Is it suitable to change the behaviour to propagate a -ENOMEM back to the caller or to retry allocation several times? Any ideas and feedback are appreciated, thanks! - Jerry === <4>[26819.222324] ------------[ cut here ]------------ <2>[26819.222329] kernel BUG at net/ceph/messenger.c:3279! <4>[26819.222331] invalid opcode: 0000 [#4] SMP <4>[26819.222335] Modules linked in: xt_comment ebt_arp ebtable_nat target_core_rbd xt_mac ip6table_raw iptable_raw xt_physdev xt_CT rbd target_core_iblock xfs ceph libceph vhost_scsi target_core_mod vhost_net vhost macvtap tun vringh virtio_scsi virtio_pci virtio_net virtio_mmio virtio_console virtio_blk virtio_balloon virtio_rng virtio_ring virtio kvm_intel kvm ebtable_filter ebtables ip6table_filter ip6_tables xt_conntrack xt_ipvs ip_vs_rr ip_vs_ftp ip_vs xt_nat xt_addrtype ib_iser(O) rdma_cm(O) ib_cm(O) iw_cm(O) mlx5_ib(O) mlx5_core(O) mlx4_ib(O) mlx4_core(O) ib_core(O) mlx_compat(O) iscsi_tcp(O) libiscsi_tcp(O) libiscsi(O) scsi_transport_iscsi(O) xt_LOG ipt_MASQUERADE xt_REDIRECT nf_nat_redirect iptable_nat nf_nat_masquerade_ipv4 nf_nat_ipv4 nf_nat xt_policy fbdisk(O) vport_vxlan vport_gre openvswitch nf_defrag_ipv6 gre ipvlan dummy macvlan br_netfilter bridge stp bonding xt_mark xt_set ip_set_hash_net ip_set xt_connmark 8021q ipv6 uvcvideo videobuf2_vmalloc videobuf2_memops videobuf2_core snd_usb_caiaq snd_usb_audio snd_usbmidi_lib snd_seq_midi snd_rawmidi fnotify(O) udf isofs sp5100_tco iTCO_wdt sha512_generic vfio_pci vfio_virqfd vfio_iommu_type1 vfio dm_c2f(O) ufsd(PO) jnl(O) pl2303 usbserial qm2_i2c(O) intel_ips drbd(O) flashcache(O) dm_tier_hro_algo dm_thin_pool dm_bio_prison dm_persistent_data hal_netlink(O) k10temp coretemp ixgbe mdio igb e1000e(O) mpt3sas(O) mpt2sas scsi_transport_sas raid_class usb_storage xhci_pci xhci_hcd usblp uhci_hcd ehci_pci ehci_hcd [last unloaded: libceph] <4>[26819.222452] CPU: 1 PID: 31188 Comm: qemu-system-x86 Tainted: P D W O 4.2.8 #1 <4>[26819.222454] Hardware name: INSYDE QV96/Type2 - Board Product Name1, BIOS QV96IR23 10/21/2015 <4>[26819.222456] task: ffff880411ff2280 ti: ffff8803665fc000 task.ti: ffff8803665fc000 <4>[26819.222457] RIP: 0010:[<ffffffffa0e0238f>] [<ffffffffa0e0238f>] ceph_msg_data_add_pages+0x6f/0x80 [libceph] <4>[26819.222465] RSP: 0018:ffff8803665ffa48 EFLAGS: 00010246 <4>[26819.222466] RAX: 0000000000000000 RBX: ffff880360509600 RCX: ffff88045e258af8 <4>[26819.222468] RDX: 000000000000003a RSI: ffff88045e258af8 RDI: 000000000000003c <4>[26819.222469] RBP: ffff8803665ffa68 R08: 0000000000000001 R09: ffff88044c004640 <4>[26819.222471] R10: 0000000000002201 R11: 000000000000003c R12: 0000000000001000 <4>[26819.222473] R13: 0000000000000000 R14: ffff880276d8ba20 R15: ffff880358e73061 <4>[26819.222475] FS: 00007fcf7d4f7700(0000) GS:ffff88045e240000(0000) knlGS:0000000000000000 <4>[26819.222476] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 <4>[26819.222478] CR2: 0000000006e6c150 CR3: 00000004428ae000 CR4: 00000000001426e0 <4>[26819.222479] Stack: <4>[26819.222481] ffff88041c630a28 ffff880360509600 0000000000002201 ffff88041c630918 <4>[26819.222484] ffff8803665ffa88 ffffffffa0e09666 0000000000000000 ffff88041c630918 <4>[26819.222488] ffff8803665ffaf8 ffffffffa0e09dde 000000007eab1000 0000006400001000 <4>[26819.222492] Call Trace: <4>[26819.222497] [<ffffffffa0e09666>] ceph_osdc_msg_data_add+0x56/0xa0 [libceph] <4>[26819.222501] [<ffffffffa0e09dde>] ceph_osdc_build_request+0x72e/0x770 [libceph] <4>[26819.222506] [<ffffffffa0e49879>] ceph_direct_read_write+0x4b9/0xc50 [ceph] <4>[26819.222510] [<ffffffff81aba835>] ? _raw_spin_lock+0x5/0x30 <4>[26819.222514] [<ffffffffa0e4bc65>] ceph_write_iter+0x3c5/0xc00 [ceph] <4>[26819.222518] [<ffffffff810e028b>] ? futex_wait+0x1fb/0x250 <4>[26819.222522] [<ffffffff81137bd6>] ? find_get_pages_tag+0xf6/0x170 <4>[26819.222525] [<ffffffff810d07c0>] ? hrtimer_forward+0x150/0x150 <4>[26819.222529] [<ffffffff81193a8a>] __vfs_write+0xaa/0xe0 <4>[26819.222532] [<ffffffff8119415a>] vfs_write+0xea/0x1f0 <4>[26819.222535] [<ffffffff811951eb>] SyS_pwrite64+0x6b/0xa0 <4>[26819.222537] [<ffffffff81abab57>] entry_SYSCALL_64_fastpath+0x12/0x6a <4>[26819.222539] Code: 44 89 68 28 48 8b 53 78 48 8d 4b 70 48 89 43 78 48 89 08 48 89 50 08 48 89 02 4c 01 63 68 5b 41 5c 41 5d 41 5e 5d c3 0f 0b 0f 0b <0f> 0b 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 e8 eb ab cb <1>[26819.222585] RIP [<ffffffffa0e0238f>] ceph_msg_data_add_pages+0x6f/0x80 [libceph] <4>[26819.222589] RSP <ffff8803665ffa48> <4>[26819.222600] ---[ end trace 62528a297c4328d8 ]---
