bisecting cause commit starting from 2d63ba3e41db3ceb0d23924ed2879b910276e24c
building syzkaller on 8fd428a197f1ff27bdb6d3d359745e2756133d01
testing commit 2d63ba3e41db3ceb0d23924ed2879b910276e24c with gcc (GCC) 8.1.0
all runs: crashed: WARNING: refcount bug in cdev_get
testing release v5.2
testing commit 0ecfebd2b52404ae0c54a878c872bb93363ada36 with gcc (GCC) 8.1.0
all runs: crashed: WARNING: refcount bug in cdev_get
testing release v5.1
testing commit e93c9c99a629c61837d5a7fc2120cd2b6c70dbdd with gcc (GCC) 8.1.0
all runs: crashed: WARNING: refcount bug in cdev_get
testing release v5.0
testing commit 1c163f4c7b3f621efff9b28a47abb36f7378d783 with gcc (GCC) 8.1.0
all runs: crashed: WARNING: refcount bug in cdev_get
testing release v4.20
testing commit 8fe28cb58bcb235034b64cbbb7550a8a43fd88be with gcc (GCC) 8.1.0
all runs: crashed: WARNING: refcount bug in cdev_get
testing release v4.19
testing commit 84df9525b0c27f3ebc2ebb1864fa62a97fdedb7d with gcc (GCC) 8.1.0
all runs: crashed: WARNING: refcount bug in cdev_get
testing release v4.18
testing commit 94710cac0ef4ee177a63b5227664b38c95bbf703 with gcc (GCC) 8.1.0
all runs: crashed: WARNING: refcount bug in cdev_get
testing release v4.17
testing commit 29dcea88779c856c7dc92040a0c01233263101d4 with gcc (GCC) 8.1.0
all runs: crashed: WARNING: refcount bug in cdev_get
testing release v4.16
testing commit 0adb32858b0bddf4ada5f364a84ed60b196dbcda with gcc (GCC) 8.1.0
all runs: crashed: WARNING: refcount bug in cdev_get
testing release v4.15
testing commit d8a5b80568a9cb66810e75b182018e9edb68e8ff with gcc (GCC) 8.1.0
run #0: crashed: WARNING: refcount bug in cdev_get
run #1: crashed: WARNING: refcount bug in cdev_get
run #2: crashed: WARNING: refcount bug in cdev_get
run #3: crashed: WARNING: refcount bug in cdev_get
run #4: crashed: WARNING: refcount bug in cdev_get
run #5: crashed: WARNING: refcount bug in cdev_get
run #6: OK
run #7: OK
run #8: OK
run #9: OK
testing release v4.14
testing commit bebc6082da0a9f5d47a1ea2edc099bf671058bd4 with gcc (GCC) 8.1.0
run #0: crashed: WARNING: refcount bug in cdev_get
run #1: crashed: WARNING: refcount bug in cdev_get
run #2: crashed: WARNING: refcount bug in cdev_get
run #3: OK
run #4: OK
run #5: OK
run #6: OK
run #7: OK
run #8: OK
run #9: OK
testing release v4.13
testing commit 569dbb88e80deb68974ef6fdd6a13edb9d686261 with gcc (GCC) 8.1.0
run #0: crashed: WARNING: refcount bug in cdev_get
run #1: crashed: WARNING: refcount bug in cdev_get
run #2: crashed: WARNING: refcount bug in cdev_get
run #3: crashed: WARNING: refcount bug in cdev_get
run #4: crashed: WARNING: refcount bug in cdev_get
run #5: crashed: WARNING: refcount bug in cdev_get
run #6: OK
run #7: OK
run #8: OK
run #9: crashed: WARNING: refcount bug in cdev_get
testing release v4.12
testing commit 6f7da290413ba713f0cdd9ff1a2a9bb129ef4f6c with gcc (GCC) 8.1.0
run #0: crashed: WARNING: refcount bug in cdev_get
run #1: crashed: WARNING: refcount bug in cdev_get
run #2: crashed: WARNING: refcount bug in cdev_get
run #3: crashed: WARNING: refcount bug in cdev_get
run #4: crashed: WARNING: refcount bug in cdev_get
run #5: crashed: WARNING: refcount bug in cdev_get
run #6: crashed: WARNING: refcount bug in cdev_get
run #7: OK
run #8: OK
run #9: OK
testing release v4.11
testing commit a351e9b9fc24e982ec2f0e76379a49826036da12 with gcc (GCC) 7.3.0
run #0: crashed: WARNING: refcount bug in cdev_get
run #1: crashed: WARNING: refcount bug in cdev_get
run #2: crashed: WARNING: refcount bug in cdev_get
run #3: OK
run #4: OK
run #5: OK
run #6: OK
run #7: OK
run #8: OK
run #9: OK
testing release v4.10
testing commit c470abd4fde40ea6a0846a2beab642a578c0b8cd with gcc (GCC) 5.5.0
run #0: crashed: WARNING in kobject_get
run #1: crashed: WARNING in kobject_get
run #2: crashed: WARNING in kobject_get
run #3: crashed: WARNING in kobject_get
run #4: crashed: WARNING in kobject_get
run #5: crashed: WARNING in kobject_get
run #6: crashed: WARNING in kobject_get
run #7: OK
run #8: OK
run #9: OK
testing release v4.9
testing commit 69973b830859bc6529a7a0468ba0d80ee5117826 with gcc (GCC) 5.5.0
run #0: crashed: WARNING in kobject_get
run #1: crashed: WARNING in kobject_get
run #2: crashed: WARNING in kobject_get
run #3: crashed: WARNING in kobject_get
run #4: crashed: WARNING in kobject_get
run #5: OK
run #6: OK
run #7: OK
run #8: OK
run #9: OK
testing release v4.8
testing commit c8d2bc9bc39ebea8437fd974fdbc21847bb897a3 with gcc (GCC) 5.5.0
run #0: crashed: WARNING in kobject_get
run #1: crashed: WARNING in kobject_get
run #2: crashed: WARNING in kobject_get
run #3: basic kernel testing failed: failed to copy test binary to VM: failed to run ["scp" "-P" "22" "-F" "/dev/null" "-o" "UserKnownHostsFile=/dev/null" "-o" "BatchMode=yes" "-o" "IdentitiesOnly=yes" "-o" "StrictHostKeyChecking=no" "-o" "ConnectTimeout=10" "-i" "/syzkaller/jobs/linux/workdir/image/key" "/tmp/syz-executor489376535" "root@10.128.15.193:./syz-executor489376535"]: exit status 1
ssh: connect to host 10.128.15.193 port 22: Connection timed out
lost connection

run #4: OK
run #5: OK
run #6: OK
run #7: OK
run #8: OK
run #9: OK
testing release v4.7
testing commit 523d939ef98fd712632d93a5a2b588e477a7565e with gcc (GCC) 5.5.0
run #0: crashed: WARNING in kobject_get
run #1: crashed: WARNING in kobject_get
run #2: crashed: WARNING in kobject_get
run #3: OK
run #4: OK
run #5: OK
run #6: crashed: WARNING in kobject_get
run #7: OK
run #8: OK
run #9: crashed: WARNING in kobject_get
testing release v4.6
testing commit 2dcd0af568b0cf583645c8a317dd12e344b1c72a with gcc (GCC) 5.5.0
run #0: crashed: WARNING in kobject_get
run #1: crashed: WARNING in kobject_get
run #2: OK
run #3: OK
run #4: OK
run #5: OK
run #6: OK
run #7: OK
run #8: OK
run #9: OK
testing release v4.5
testing commit b562e44f507e863c6792946e4e1b1449fbbac85d with gcc (GCC) 5.5.0
run #0: crashed: WARNING in kobject_get
run #1: crashed: WARNING in kobject_get
run #2: crashed: WARNING in kobject_get
run #3: crashed: WARNING in kobject_get
run #4: crashed: WARNING in kobject_get
run #5: crashed: WARNING in kobject_get
run #6: OK
run #7: OK
run #8: OK
run #9: crashed: WARNING in kobject_get
testing release v4.4
testing commit afd2ff9b7e1b367172f18ba7f693dfb62bdcb2dc with gcc (GCC) 5.5.0
run #0: crashed: WARNING in kobject_get
run #1: crashed: WARNING in kobject_get
run #2: crashed: WARNING in kobject_get
run #3: crashed: WARNING in kobject_get
run #4: crashed: WARNING in kobject_get
run #5: OK
run #6: OK
run #7: OK
run #8: OK
run #9: OK
testing release v4.3
testing commit 6a13feb9c82803e2b815eca72fa7a9f5561d7861 with gcc (GCC) 5.5.0
run #0: crashed: WARNING in kobject_get
run #1: crashed: WARNING in kobject_get
run #2: crashed: WARNING in kobject_get
run #3: crashed: WARNING in kobject_get
run #4: basic kernel testing failed: failed to copy test binary to VM: failed to run ["scp" "-P" "22" "-F" "/dev/null" "-o" "UserKnownHostsFile=/dev/null" "-o" "BatchMode=yes" "-o" "IdentitiesOnly=yes" "-o" "StrictHostKeyChecking=no" "-o" "ConnectTimeout=10" "-i" "/syzkaller/jobs/linux/workdir/image/key" "/tmp/syz-executor063465440" "root@10.128.0.147:./syz-executor063465440"]: exit status 1
ssh: connect to host 10.128.0.147 port 22: Connection timed out
lost connection

run #5: basic kernel testing failed: failed to copy test binary to VM: failed to run ["scp" "-P" "22" "-F" "/dev/null" "-o" "UserKnownHostsFile=/dev/null" "-o" "BatchMode=yes" "-o" "IdentitiesOnly=yes" "-o" "StrictHostKeyChecking=no" "-o" "ConnectTimeout=10" "-i" "/syzkaller/jobs/linux/workdir/image/key" "/tmp/syz-executor276027922" "root@10.128.0.183:./syz-executor276027922"]: exit status 1
ssh: connect to host 10.128.0.183 port 22: Connection timed out
lost connection

run #6: basic kernel testing failed: failed to copy test binary to VM: failed to run ["scp" "-P" "22" "-F" "/dev/null" "-o" "UserKnownHostsFile=/dev/null" "-o" "BatchMode=yes" "-o" "IdentitiesOnly=yes" "-o" "StrictHostKeyChecking=no" "-o" "ConnectTimeout=10" "-i" "/syzkaller/jobs/linux/workdir/image/key" "/tmp/syz-executor098782281" "root@10.128.0.205:./syz-executor098782281"]: exit status 1
ssh: connect to host 10.128.0.205 port 22: Connection timed out
lost connection

run #7: OK
run #8: OK
run #9: OK
testing release v4.2
testing commit 64291f7db5bd8150a74ad2036f1037e6a0428df2 with gcc (GCC) 5.5.0
run #0: crashed: WARNING in kobject_get
run #1: crashed: WARNING in kobject_get
run #2: crashed: WARNING in kobject_get
run #3: OK
run #4: OK
run #5: OK
run #6: OK
run #7: OK
run #8: OK
run #9: OK
testing release v4.1
testing commit b953c0d234bc72e8489d3bf51a276c5c4ec85345 with gcc (GCC) 5.5.0
run #0: crashed: WARNING in kobject_get
run #1: crashed: WARNING in kobject_get
run #2: crashed: no output from test machine
run #3: basic kernel testing failed: failed to copy test binary to VM: failed to run ["scp" "-P" "22" "-F" "/dev/null" "-o" "UserKnownHostsFile=/dev/null" "-o" "BatchMode=yes" "-o" "IdentitiesOnly=yes" "-o" "StrictHostKeyChecking=no" "-o" "ConnectTimeout=10" "-i" "/syzkaller/jobs/linux/workdir/image/key" "/tmp/syz-executor045955285" "root@10.128.1.2:./syz-executor045955285"]: exit status 1
ssh: connect to host 10.128.1.2 port 22: Connection timed out
lost connection

run #4: OK
run #5: OK
run #6: OK
run #7: OK
run #8: OK
run #9: OK
revisions tested: 24, total time: 5h30m6.912670435s (build: 1h52m44.028752862s, test: 3h29m23.353844805s)
the crash already happened on the oldest tested release
crash: no output from test machine