On Mon, Sep 28, 2020 at 02:14:16PM -0400, Tony Fischetti wrote: > After a length git bisection, I determined the commit that introduced > a change that ultimately caused a bug/oops null dereference (see below > for relevant syslog entries) was 008cfe4418b3dbda2ff.. (mm: Introduce > mm_struct.has_pinned) > > The RIP (according to syslog) occurs in function > `__get_user_pages_remote` and the last function to call it from the > i915 code is `gem_userptr_get_pages_worker` > More specifically, it appears to be the call to > `pin_user_pages_remote` in `gem_userptr_get_pages_worker` in > drivers/gpu/drm/i915/gem/i915_gem_userptr.c that directly leads to the > oops. > > Unfortunately, I don't know enough to try to fix and share the fix > myself, but I hope the information I provided is helpful. Please let > me know if there is any further information I can provide that might > be of use. > > BUG: kernel NULL pointer dereference, address: 0000000000000054 > #PF: supervisor write access in kernel mode > #PF: error_code(0x0002) - not-present page > Oops: 0002 [#1] PREEMPT SMP NOPTI > CPU: 8 PID: 497 Comm: kworker/u25:0 Not tainted > 5.9.0-rc7-alice-investigate-3+ #2 > Hardware name: LENOVO 10ST001QUS/312A, BIOS M1UKT4BA 11/11/2019 > Workqueue: i915-userptr-acquire __i915_gem_userptr_get_pages_worker [i915] > RIP: 0010:__get_user_pages_remote+0xa0/0x2d0 > Code: 85 e7 01 00 00 83 3b 01 0f 85 e0 01 00 00 f7 c1 00 00 04 00 0f > 84 12 01 00 00 65 48 8b 04 25 00 6d 01 00 48 8b 80 58 03 00 00 <c7> 40 > 54 01 00 00 00 c6 04 24 00 4d 8d 6f 68 48 c7 44 24 10 00 00 > RSP: 0018:ffffa1a58086bde0 EFLAGS: 00010206 > RAX: 0000000000000000 RBX: ffffa1a58086be64 RCX: 0000000000040001 > RDX: 00000000000007e9 RSI: 00007f532f800000 RDI: ffff92f22d89c480 > RBP: 00007f532f800000 R08: ffff92f23a188000 R09: 0000000000000000 > R10: 0000000000000000 R11: ffffa1a58086bcfd R12: ffff92f23a188000 > R13: ffff92f22d89c480 R14: 0000000000042003 R15: ffff92f22d89c480 > FS: 0000000000000000(0000) GS:ffff92f23e400000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000054 CR3: 0000000016c0a002 CR4: 00000000001706e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > __i915_gem_userptr_get_pages_worker+0x1ec/0x392 [i915] > process_one_work+0x1c7/0x310 > worker_thread+0x28/0x3c0 > ? set_worker_desc+0xb0/0xb0 > kthread+0x123/0x140 > ? kthread_use_mm+0xe0/0xe0 > ret_from_fork+0x1f/0x30 > Modules linked in: snd_hda_codec_hdmi snd_hda_codec_realtek > snd_hda_codec_generic ledtrig_audio iwlmvm mac80211 libarc4 > x86_pkg_temp_thermal intel_powerclamp iwlwifi coretemp i915 > crct10dif_pclmul crc32_pclmul crc32c_intel i2c_algo_bit > ghash_clmulni_intel drm_kms_helper syscopyarea sysfillrect sysimgblt > fb_sys_fops cec mei_hdcp wmi_bmof snd_hda_intel drm tpm_crb > snd_intel_dspcfg intel_wmi_thunderbolt snd_hda_codec snd_hwdep > aesni_intel crypto_simd glue_helper snd_hda_core cfg80211 i2c_i801 > snd_pcm intel_cstate pcspkr snd_timer mei_me i2c_smbus mei i2c_core > thermal wmi tpm_tis tpm_tis_core tpm rng_core acpi_pad ppdev lp > ip_tables x_tables > CR2: 0000000000000054 > ---[ end trace 8d080e8b96289c9e ]--- >
Hi, Tony, This is also reported elsewhere and the proper fix should be here: https://lore.kernel.org/intel-gfx/20200928134915.GA5904@xz-x1 Thanks for the report, and sorry for the trouble! -- Peter Xu
