| Message ID | 20220225215705.248707-2-alan.previn.teres.alexis@intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Fix i915 error_state_read ptr use | expand |
Hi Alan,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on drm-intel/for-linux-next]
[also build test WARNING on drm-tip/drm-tip drm-exynos/exynos-drm-next drm/drm-next tegra-drm/drm/tegra/for-next v5.17-rc5 next-20220224]
[cannot apply to airlied/drm-next]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/0day-ci/linux/commits/Alan-Previn/Fix-i915-error_state_read-ptr-use/20220226-055549
base: git://anongit.freedesktop.org/drm-intel for-linux-next
config: i386-randconfig-a011 (https://download.01.org/0day-ci/archive/20220226/202202261049.pxCmgeWV-lkp@intel.com/config)
compiler: clang version 15.0.0 (https://github.com/llvm/llvm-project d271fc04d5b97b12e6b797c6067d3c96a8d7470e)
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# https://github.com/0day-ci/linux/commit/4ae08e2ae5d3ff4e465a35b05010e44d02b59aab
git remote add linux-review https://github.com/0day-ci/linux
git fetch --no-tags linux-review Alan-Previn/Fix-i915-error_state_read-ptr-use/20220226-055549
git checkout 4ae08e2ae5d3ff4e465a35b05010e44d02b59aab
# save the config file to linux build tree
mkdir build_dir
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=i386 SHELL=/bin/bash drivers/gpu/drm/i915/
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>
All warnings (new ones prefixed by >>):
>> drivers/gpu/drm/i915/i915_sysfs.c:447:3: warning: variable 'ret' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
if (off < len) {
^~~~~~~~~~~~~~
include/linux/compiler.h:56:28: note: expanded from macro 'if'
#define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) )
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:58:30: note: expanded from macro '__trace_if_var'
#define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond))
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/gpu/drm/i915/i915_sysfs.c:453:9: note: uninitialized use occurs here
return ret;
^~~
drivers/gpu/drm/i915/i915_sysfs.c:447:3: note: remove the 'if' if its condition is always true
if (off < len) {
^~~~~~~~~~~~~~~
include/linux/compiler.h:56:23: note: expanded from macro 'if'
#define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) )
^
drivers/gpu/drm/i915/i915_sysfs.c:435:13: note: initialize the variable 'ret' to silence this warning
ssize_t ret;
^
= 0
1 warning generated.
vim +447 drivers/gpu/drm/i915/i915_sysfs.c
431
432 struct device *kdev = kobj_to_dev(kobj);
433 struct drm_i915_private *i915 = kdev_minor_to_i915(kdev);
434 struct i915_gpu_coredump *gpu;
435 ssize_t ret;
436
437 gpu = i915_first_error_state(i915);
438 if (IS_ERR(gpu)) {
439 ret = PTR_ERR(gpu);
440 } else if (gpu) {
441 ret = i915_gpu_coredump_copy_to_buffer(gpu, buf, off, count);
442 i915_gpu_coredump_put(gpu);
443 } else {
444 const char *str = "No error state collected\n";
445 size_t len = strlen(str);
446
> 447 if (off < len) {
448 ret = min_t(size_t, count, len - off);
449 memcpy(buf, str + off, ret);
450 }
451 }
452
453 return ret;
454 }
455
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c index a4d1759375b9..9171c340c41e 100644 --- a/drivers/gpu/drm/i915/i915_sysfs.c +++ b/drivers/gpu/drm/i915/i915_sysfs.c @@ -444,8 +444,10 @@ 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;
Fix our pointer offset usage in error_state_read when there is no i915_gpu_coredump but buf offset is non-zero. 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: 5014 [ 5590.803000] BUG: unable to handle page fault for address: ffffffffa0b0e000 5015 [ 5590.803009] #PF: supervisor read access in kernel mode 5016 [ 5590.803013] #PF: error_code(0x0000) - not-present page 5017 [ 5590.803016] PGD 5814067 P4D 5814067 PUD 5815063 PMD 109de4067 PTE 0 5018 [ 5590.803022] Oops: 0000 [#1] PREEMPT SMP NOPTI 5019 [ 5590.803026] CPU: 5 PID: 13656 Comm: i915_hangman Tainted: G U 5.17.0-rc5-ups69-guc-err-capt-rev6+ #136 5020 [ 5590.803033] Hardware name: Intel Corporation Alder Lake Client Platform/AlderLake-M LP4x RVP, BIOS ADLPFWI1.R00.3031.A02.2201171222 01/17/2022 5021 [ 5590.803039] RIP: 0010:memcpy_erms+0x6/0x10 5022 [ 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 5023 [ 5590.803054] RSP: 0018:ffffc90003a8fdf0 EFLAGS: 00010282 5024 [ 5590.803057] RAX: ffff888107ee9000 RBX: ffff888108cb1a00 RCX: 0000000000000f8f 5025 [ 5590.803061] RDX: 0000000000001000 RSI: ffffffffa0b0e000 RDI: ffff888107ee9071 5026 [ 5590.803065] RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001 5027 [ 5590.803069] R10: 0000000000000001 R11: 0000000000000002 R12: 0000000000000019 5028 [ 5590.803073] R13: 0000000000174fff R14: 0000000000001000 R15: ffff888107ee9000 5029 [ 5590.803077] FS: 00007f62a99bee80(0000) GS:ffff88849f880000(0000) knlGS:0000000000000000 5030 [ 5590.803082] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 5031 [ 5590.803085] CR2: ffffffffa0b0e000 CR3: 000000010a1a8004 CR4: 0000000000770ee0 5032 [ 5590.803089] PKRU: 55555554 5033 [ 5590.803091] Call Trace: 5034 [ 5590.803093] <TASK> 5035 [ 5590.803096] error_state_read+0xa1/0xd0 [i915] 5036 [ 5590.803175] kernfs_fop_read_iter+0xb2/0x1b0 5037 [ 5590.803180] new_sync_read+0x116/0x1a0 5038 [ 5590.803185] vfs_read+0x114/0x1b0 5039 [ 5590.803189] ksys_read+0x63/0xe0 5040 [ 5590.803193] do_syscall_64+0x38/0xc0 5041 [ 5590.803197] entry_SYSCALL_64_after_hwframe+0x44/0xae 5042 [ 5590.803201] RIP: 0033:0x7f62aaea5912 5043 [ 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 5044 [ 5590.803213] RSP: 002b:00007fff5b659ae8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 5045 [ 5590.803218] RAX: ffffffffffffffda RBX: 0000000000100000 RCX: 00007f62aaea5912 5046 [ 5590.803221] RDX: 000000000008b000 RSI: 00007f62a8c4000f RDI: 0000000000000006 5047 [ 5590.803225] RBP: 00007f62a8bcb00f R08: 0000000000200010 R09: 0000000000101000 5048 [ 5590.803229] R10: 0000000000000001 R11: 0000000000000246 R12: 0000000000000006 5049 [ 5590.803233] R13: 0000000000075000 R14: 00007f62a8acb010 R15: 0000000000200000 5050 [ 5590.803238] </TASK> 5051 [ 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] 5052 [ 5590.803277] CR2: ffffffffa0b0e000 5053 [ 5590.803280] ---[ end trace 0000000000000000 ]--- Signed-off-by: Alan Previn <alan.previn.teres.alexis@intel.com> --- drivers/gpu/drm/i915/i915_sysfs.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)