Messages in this thread | | | From | Christophe LEROY <> | Subject | UBSAN: Undefined behaviour in kernel/rcu/tree_plugin.h in 4.20-rc1 | Date | Fri, 9 Nov 2018 17:50:56 +0100 |
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Paul,
I get the following UBSAN reports in 4.20-rc1 on an MPC8321E (powerpc/book3s/32)
I bisected it to 3e31009898699dfc ("rcu: Defer reporting RCU-preempt quiescent states when disabled")
Thanks Christophe
[ 4.919995] ================================================================================ [ 4.928428] UBSAN: Undefined behaviour in kernel/rcu/tree_plugin.h:623:28 [ 4.935198] signed integer overflow: [ 4.938766] 0 - -2147483648 cannot be represented in type 'int' [ 4.944678] CPU: 0 PID: 119 Comm: mkdir Not tainted 4.19.0-rc1-s3k-dev-00005-g5a60513 #214 [ 4.952908] Call Trace: [ 4.955382] [dec4fd20] [c02cb0d0] ubsan_epilogue+0x18/0x74 (unreliable) [ 4.962003] [dec4fd30] [c02cb5e0] handle_overflow+0xd0/0xe0 [ 4.967588] [dec4fdb0] [c007b424] rcu_preempt_deferred_qs+0xc0/0xc8 [ 4.973857] [dec4fdd0] [c007be28] rcu_note_context_switch+0x74/0x608 [ 4.980217] [dec4fe10] [c064b790] __schedule+0x58/0x6e0 [ 4.985448] [dec4fe50] [c064bfdc] preempt_schedule_common+0x48/0x9c [ 4.991717] [dec4fe70] [c01308c8] handle_mm_fault+0x10fc/0x1ecc [ 4.997639] [dec4fee0] [c001339c] do_page_fault+0x10c/0x760 [ 5.003225] [dec4ff40] [c001234c] handle_page_fault+0x14/0x40 [ 5.008968] --- interrupt: 401 at 0xff9cff8 [ 5.008968] LR = 0xfeefd78 [ 5.016170] ================================================================================ [ 5.024591] ================================================================================ [ 5.033005] UBSAN: Undefined behaviour in kernel/rcu/tree_plugin.h:627:28 [ 5.039775] signed integer overflow: [ 5.043342] -2147483648 + -2147483648 cannot be represented in type 'int' [ 5.050118] CPU: 0 PID: 119 Comm: mkdir Not tainted 4.19.0-rc1-s3k-dev-00005-g5a60513 #214 [ 5.058348] Call Trace: [ 5.060813] [dec4fd20] [c02cb0d0] ubsan_epilogue+0x18/0x74 (unreliable) [ 5.067433] [dec4fd30] [c02cb5e0] handle_overflow+0xd0/0xe0 [ 5.073014] [dec4fdb0] [c007b408] rcu_preempt_deferred_qs+0xa4/0xc8 [ 5.079283] [dec4fdd0] [c007be28] rcu_note_context_switch+0x74/0x608 [ 5.085640] [dec4fe10] [c064b790] __schedule+0x58/0x6e0 [ 5.090871] [dec4fe50] [c064bfdc] preempt_schedule_common+0x48/0x9c [ 5.097139] [dec4fe70] [c01308c8] handle_mm_fault+0x10fc/0x1ecc [ 5.103059] [dec4fee0] [c001339c] do_page_fault+0x10c/0x760 [ 5.108642] [dec4ff40] [c001234c] handle_page_fault+0x14/0x40 [ 5.114385] --- interrupt: 401 at 0xff9cff8 [ 5.114385] LR = 0xfeefd78 [ 5.121588] ================================================================================
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