Messages in this thread | | | Date | Sun, 23 Aug 2015 19:45:15 -0700 | Subject | Re: [BUG] arm: kgdb: patch_text() in kgdb_arch_set_breakpoint() may sleep | From | Doug Anderson <> |
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Aapo,
Including the stack trace with this would have been helpful, though it's not too hard to reproduce. Here it is:
[ 416.510559] BUG: scheduling while atomic: swapper/0/0/0x00010007 [ 416.516554] Modules linked in: [ 416.519614] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.2.0-rc7-00133-geb63b34 #1073 [ 416.527341] Hardware name: Rockchip (Device Tree) [ 416.532042] [<c0017a4c>] (unwind_backtrace) from [<c00133d4>] (show_stack+0x20/0x24) [ 416.539772] [<c00133d4>] (show_stack) from [<c05400e8>] (dump_stack+0x84/0xb8) [ 416.546983] [<c05400e8>] (dump_stack) from [<c004913c>] (__schedule_bug+0x54/0x6c) [ 416.554540] [<c004913c>] (__schedule_bug) from [<c054065c>] (__schedule+0x80/0x668) [ 416.562183] [<c054065c>] (__schedule) from [<c0540cfc>] (schedule+0xb8/0xd4) [ 416.569219] [<c0540cfc>] (schedule) from [<c0543a3c>] (schedule_timeout+0x2c/0x234) [ 416.576861] [<c0543a3c>] (schedule_timeout) from [<c05417c0>] (wait_for_common+0xf4/0x188) [ 416.585109] [<c05417c0>] (wait_for_common) from [<c0541874>] (wait_for_completion+0x20/0x24) [ 416.593531] [<c0541874>] (wait_for_completion) from [<c00a0104>] (__stop_cpus+0x58/0x70) [ 416.601608] [<c00a0104>] (__stop_cpus) from [<c00a0580>] (stop_cpus+0x3c/0x54) [ 416.608817] [<c00a0580>] (stop_cpus) from [<c00a06c4>] (__stop_machine+0xcc/0xe8) [ 416.616286] [<c00a06c4>] (__stop_machine) from [<c00a0714>] (stop_machine+0x34/0x44) [ 416.624016] [<c00a0714>] (stop_machine) from [<c00173e8>] (patch_text+0x28/0x34) [ 416.631399] [<c00173e8>] (patch_text) from [<c001733c>] (kgdb_arch_set_breakpoint+0x40/0x4c) [ 416.639823] [<c001733c>] (kgdb_arch_set_breakpoint) from [<c00a0d68>] (kgdb_validate_break_address+0x2c/0x60) [ 416.649719] [<c00a0d68>] (kgdb_validate_break_address) from [<c00a0e90>] (dbg_set_sw_break+0x1c/0xdc) [ 416.658922] [<c00a0e90>] (dbg_set_sw_break) from [<c00a2e88>] (gdb_serial_stub+0x9c4/0xba4) [ 416.667259] [<c00a2e88>] (gdb_serial_stub) from [<c00a11cc>] (kgdb_cpu_enter+0x1f8/0x60c) [ 416.675423] [<c00a11cc>] (kgdb_cpu_enter) from [<c00a18cc>] (kgdb_handle_exception+0x19c/0x1d0) [ 416.684106] [<c00a18cc>] (kgdb_handle_exception) from [<c0016f7c>] (kgdb_compiled_brk_fn+0x30/0x3c) [ 416.693135] [<c0016f7c>] (kgdb_compiled_brk_fn) from [<c00091a4>] (do_undefinstr+0x1a4/0x20c) [ 416.701643] [<c00091a4>] (do_undefinstr) from [<c001400c>] (__und_svc_finish+0x0/0x34) [ 416.709543] Exception stack(0xc07c1ce8 to 0xc07c1d30) [ 416.714584] 1ce0: 00000000 c07c6504 c086e290 c086e294 c086e294 c086e290 [ 416.722745] 1d00: c07c6504 00000067 00000001 c07c2100 00000027 c07c1d4c c07c1d50 c07c1d30 [ 416.730905] 1d20: c00a0990 c00a08d0 60000193 ffffffff [ 416.735947] [<c001400c>] (__und_svc_finish) from [<c00a08d0>] (kgdb_breakpoint+0x58/0x94) [ 416.744110] [<c00a08d0>] (kgdb_breakpoint) from [<c00a0990>] (sysrq_handle_dbg+0x58/0x6c) [ 416.752273] [<c00a0990>] (sysrq_handle_dbg) from [<c02c230c>] (__handle_sysrq+0xac/0x15c) [ 416.760437] [<c02c230c>] (__handle_sysrq) from [<c02c23ec>] (handle_sysrq+0x30/0x34)
Kees: I think you've dealt with a lot more of these types of issues than I have. Any quick thoughts? If not I can put it on my long-term list of things to do, but until then we could always just post a Revert...
-Doug
On Wed, Aug 5, 2015 at 8:50 AM, Aapo Vienamo <avienamo@nvidia.com> wrote: > Hi, > > The breakpoint setting code in arch/arm/kernel/kgdb.c calls > patch_text(), which ends up trying to sleep while in interrupt context. > The bug was introduced by commit: 23a4e40 arm: kgdb: Handle read-only > text / modules. The resulting behavior is "BUG: scheduling while > atomic..." when setting a breakpoint in kgdb. This was tested on an > Nvidia Jetson TK1 board with 4.2.0-rc5-next-20150805 kernel. > > Regards, > Aapo Vienamo
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