[Intel-gfx] [PATCH v4 1/1] drm/i915/reset: Fix error_state_read ptr + offset use
John Harrison
john.c.harrison at intel.com
Thu May 26 01:15:12 UTC 2022
On 3/10/2022 16:43, Alan Previn wrote:
> Fix our pointer offset usage in error_state_read
> when there is no i915_gpu_coredump but buf offset
> is non-zero.
>
> Fixes: 0e39037b3165 ("drm/i915: Cache the error string")
>
> This fixes a kernel page fault can happen when
> multiple tests are running concurrently in a loop
> and one is producing engine resets and consuming
> the i915 error_state dump while the other is
> forcing full GT resets. (takes a while to trigger).
>
> The dmesg call trace:
>
> [ 5590.803000] BUG: unable to handle page fault for address:
> ffffffffa0b0e000
> [ 5590.803009] #PF: supervisor read access in kernel mode
> [ 5590.803013] #PF: error_code(0x0000) - not-present page
> [ 5590.803016] PGD 5814067 P4D 5814067 PUD 5815063 PMD 109de4067
> PTE 0
> [ 5590.803022] Oops: 0000 [#1] PREEMPT SMP NOPTI
> [ 5590.803026] CPU: 5 PID: 13656 Comm: i915_hangman Tainted: G U
> 5.17.0-rc5-ups69-guc-err-capt-rev6+ #136
> [ 5590.803033] Hardware name: Intel Corporation Alder Lake Client
> Platform/AlderLake-M LP4x RVP, BIOS ADLPFWI1.R00.
> 3031.A02.2201171222 01/17/2022
> [ 5590.803039] RIP: 0010:memcpy_erms+0x6/0x10
> [ 5590.803045] Code: fe ff ff cc eb 1e 0f 1f 00 48 89 f8 48 89 d1
> 48 c1 e9 03 83 e2 07 f3 48 a5 89 d1 f3 a4 c3
> 66 0f 1f 44 00 00 48 89 f8 48 89 d1 <f3> a4
> c3 0f 1f 80 00 00 00 00 48 89 f8 48 83 fa 20
> 72 7e 40 38 fe
> [ 5590.803054] RSP: 0018:ffffc90003a8fdf0 EFLAGS: 00010282
> [ 5590.803057] RAX: ffff888107ee9000 RBX: ffff888108cb1a00
> RCX: 0000000000000f8f
> [ 5590.803061] RDX: 0000000000001000 RSI: ffffffffa0b0e000
> RDI: ffff888107ee9071
> [ 5590.803065] RBP: 0000000000000000 R08: 0000000000000001
> R09: 0000000000000001
> [ 5590.803069] R10: 0000000000000001 R11: 0000000000000002
> R12: 0000000000000019
> [ 5590.803073] R13: 0000000000174fff R14: 0000000000001000
> R15: ffff888107ee9000
> [ 5590.803077] FS: 00007f62a99bee80(0000) GS:ffff88849f880000(0000)
> knlGS:0000000000000000
> [ 5590.803082] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 5590.803085] CR2: ffffffffa0b0e000 CR3: 000000010a1a8004
> CR4: 0000000000770ee0
> [ 5590.803089] PKRU: 55555554
> [ 5590.803091] Call Trace:
> [ 5590.803093] <TASK>
> [ 5590.803096] error_state_read+0xa1/0xd0 [i915]
> [ 5590.803175] kernfs_fop_read_iter+0xb2/0x1b0
> [ 5590.803180] new_sync_read+0x116/0x1a0
> [ 5590.803185] vfs_read+0x114/0x1b0
> [ 5590.803189] ksys_read+0x63/0xe0
> [ 5590.803193] do_syscall_64+0x38/0xc0
> [ 5590.803197] entry_SYSCALL_64_after_hwframe+0x44/0xae
> [ 5590.803201] RIP: 0033:0x7f62aaea5912
> [ 5590.803204] Code: c0 e9 b2 fe ff ff 50 48 8d 3d 5a b9 0c 00 e8 05
> 19 02 00 0f 1f 44 00 00 f3 0f 1e fa 64 8b 04 25
> 18 00 00 00 85 c0 75 10 0f 05 <48> 3d 00 f0 ff
> ff 77 56 c3 0f 1f 44 00 00 48 83 ec 28 48 89 54 24
> [ 5590.803213] RSP: 002b:00007fff5b659ae8 EFLAGS: 00000246
> ORIG_RAX: 0000000000000000
> [ 5590.803218] RAX: ffffffffffffffda RBX: 0000000000100000
> RCX: 00007f62aaea5912
> [ 5590.803221] RDX: 000000000008b000 RSI: 00007f62a8c4000f
> RDI: 0000000000000006
> [ 5590.803225] RBP: 00007f62a8bcb00f R08: 0000000000200010
> R09: 0000000000101000
> [ 5590.803229] R10: 0000000000000001 R11: 0000000000000246
> R12: 0000000000000006
> [ 5590.803233] R13: 0000000000075000 R14: 00007f62a8acb010
> R15: 0000000000200000
> [ 5590.803238] </TASK>
> [ 5590.803240] Modules linked in: i915 ttm drm_buddy drm_dp_helper
> drm_kms_helper syscopyarea sysfillrect sysimgblt
> fb_sys_fops prime_numbers nfnetlink br_netfilter
> overlay mei_pxp mei_hdcp x86_pkg_temp_thermal
> coretemp kvm_intel snd_hda_codec_hdmi snd_hda_intel
> snd_intel_dspcfg snd_hda_codec snd_hwdep
> snd_hda_core snd_pcm mei_me mei fuse ip_tables
> x_tables crct10dif_pclmul e1000e crc32_pclmul ptp
> i2c_i801 ghash_clmulni_intel i2c_smbus pps_core
> [last unloa ded: ttm]
> [ 5590.803277] CR2: ffffffffa0b0e000
> [ 5590.803280] ---[ end trace 0000000000000000 ]---
>
> Signed-off-by: Alan Previn <alan.previn.teres.alexis at intel.com>
Sorry for the delay in responding to v4!
Reviewed-by: John Harrison <John.C.Harrison at Intel.com>
> ---
> drivers/gpu/drm/i915/i915_sysfs.c | 15 ++++++++++++---
> 1 file changed, 12 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c
> index a4d1759375b9..66a8880eaf19 100644
> --- a/drivers/gpu/drm/i915/i915_sysfs.c
> +++ b/drivers/gpu/drm/i915/i915_sysfs.c
> @@ -432,7 +432,14 @@ static ssize_t error_state_read(struct file *filp, struct kobject *kobj,
> struct device *kdev = kobj_to_dev(kobj);
> struct drm_i915_private *i915 = kdev_minor_to_i915(kdev);
> struct i915_gpu_coredump *gpu;
> - ssize_t ret;
> + ssize_t ret = 0;
> +
> + /*
> + * FIXME: Concurrent clients triggering resets and reading + clearing
> + * dumps can cause inconsistent sysfs reads when a user calls in with a
> + * non-zero offset to complete a prior partial read but the
> + * gpu_coredump has been cleared or replaced.
> + */
>
> gpu = i915_first_error_state(i915);
> if (IS_ERR(gpu)) {
> @@ -444,8 +451,10 @@ static ssize_t error_state_read(struct file *filp, struct kobject *kobj,
> const char *str = "No error state collected\n";
> size_t len = strlen(str);
>
> - ret = min_t(size_t, count, len - off);
> - memcpy(buf, str + off, ret);
> + if (off < len) {
> + ret = min_t(size_t, count, len - off);
> + memcpy(buf, str + off, ret);
> + }
> }
>
> return ret;
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