Le 19/05/2022 à 04:17, Guenter Roeck a écrit : > On Tue, Mar 22, 2022 at 04:40:20PM +0100, Christophe Leroy wrote: >> Once init is done, initmem is freed forever so no need to >> test system_state at every call to patch_instruction(). >> >> Use jump_label. >> >> This reduces by 2% the time needed to activate ftrace on an 8xx. >> > > It also causes the qemu mpc8544ds emulation to crash. > > BUG: Unable to handle kernel data access on write at 0xc122eb34 > Faulting instruction address: 0xc001b580 > Oops: Kernel access of bad area, sig: 11 [#1] > BE PAGE_SIZE=4K MPC8544 DS > Modules linked in: > CPU: 0 PID: 1 Comm: swapper Not tainted 5.18.0-rc7-next-20220518 #1 > NIP: c001b580 LR: c001b560 CTR: 00000003 > REGS: c5107dd0 TRAP: 0300 Not tainted (5.18.0-rc7-next-20220518) > MSR: 00009000 <EE,ME> CR: 24000882 XER: 00000000 > DEAR: c122eb34 ESR: 00800000 > GPR00: c001b560 c5107ec0 c5120020 10000000 00000000 00000078 0c000000 cfffffff > GPR08: c001e9ec 00000001 00000007 00000000 44000882 00000000 c0005178 00000000 > GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000 > GPR24: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 c1230000 > NIP [c001b580] free_initmem+0x48/0xa8 > LR [c001b560] free_initmem+0x28/0xa8 > Call Trace: > [c5107ec0] [c001b560] free_initmem+0x28/0xa8 (unreliable) > [c5107ee0] [c00051b0] kernel_init+0x38/0x150 > [c5107f00] [c001626c] ret_from_kernel_thread+0x5c/0x64 > Instruction dump: > 3fe0c123 912a00dc 90010024 48000665 3d20c218 8929fa65 2c090000 41820058 > 813feb34 2c090000 4082003c 39200001 <913feb34> 80010024 3cc0c114 83e1001c > > Reverting this patch fixes the problem. >
That's strange. I was able to reproduce the problem. Removing the __ro_after_init in front of DEFINE_STATIC_KEY_FALSE(init_mem_is_free) fixes the problem. I can't understand why, mark_readonly() is called after free_initmem(). Christophe
