[agd5f:drm-next 185/212] drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_svm.c:2067:22: warning: variable 'p' set but not used
From: kernel test robot
Date: Fri Jan 28 2022 - 02:29:13 EST
tree: https://gitlab.freedesktop.org/agd5f/linux.git drm-next
head: af60f9540e16fe6300d2e57f69484d364f76da34
commit: 367c9b0f1b8750a704070e7ae85234d591290434 [185/212] drm/amdkfd: Ensure mm remain valid in svm deferred_list work
config: x86_64-allyesconfig (https://download.01.org/0day-ci/archive/20220128/202201281547.sPuZ2yPF-lkp@xxxxxxxxx/config)
compiler: gcc-9 (Debian 9.3.0-22) 9.3.0
reproduce (this is a W=1 build):
git remote add agd5f https://gitlab.freedesktop.org/agd5f/linux.git
git fetch --no-tags agd5f drm-next
git checkout 367c9b0f1b8750a704070e7ae85234d591290434
# save the config file to linux build tree
mkdir build_dir
make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/gpu/
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@xxxxxxxxx>
All warnings (new ones prefixed by >>):
drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_svm.c: In function 'svm_range_deferred_list_work':
>> drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_svm.c:2067:22: warning: variable 'p' set but not used [-Wunused-but-set-variable]
2067 | struct kfd_process *p;
| ^
vim +/p +2067 drivers/gpu/drm/amd/amdgpu/../amdkfd/kfd_svm.c
373e3ccd859b4b Philip Yang 2021-04-19 2061
4683cfecadeb38 Philip Yang 2020-04-08 2062 static void svm_range_deferred_list_work(struct work_struct *work)
4683cfecadeb38 Philip Yang 2020-04-08 2063 {
4683cfecadeb38 Philip Yang 2020-04-08 2064 struct svm_range_list *svms;
4683cfecadeb38 Philip Yang 2020-04-08 2065 struct svm_range *prange;
4683cfecadeb38 Philip Yang 2020-04-08 2066 struct mm_struct *mm;
a0c55ecee10055 Philip Yang 2021-11-16 @2067 struct kfd_process *p;
4683cfecadeb38 Philip Yang 2020-04-08 2068
4683cfecadeb38 Philip Yang 2020-04-08 2069 svms = container_of(work, struct svm_range_list, deferred_list_work);
4683cfecadeb38 Philip Yang 2020-04-08 2070 pr_debug("enter svms 0x%p\n", svms);
4683cfecadeb38 Philip Yang 2020-04-08 2071
a0c55ecee10055 Philip Yang 2021-11-16 2072 p = container_of(svms, struct kfd_process, svms);
367c9b0f1b8750 Philip Yang 2022-01-18 2073
367c9b0f1b8750 Philip Yang 2022-01-18 2074 spin_lock(&svms->deferred_list_lock);
367c9b0f1b8750 Philip Yang 2022-01-18 2075 while (!list_empty(&svms->deferred_range_list)) {
367c9b0f1b8750 Philip Yang 2022-01-18 2076 prange = list_first_entry(&svms->deferred_range_list,
367c9b0f1b8750 Philip Yang 2022-01-18 2077 struct svm_range, deferred_list);
367c9b0f1b8750 Philip Yang 2022-01-18 2078 spin_unlock(&svms->deferred_list_lock);
367c9b0f1b8750 Philip Yang 2022-01-18 2079
367c9b0f1b8750 Philip Yang 2022-01-18 2080 pr_debug("prange 0x%p [0x%lx 0x%lx] op %d\n", prange,
367c9b0f1b8750 Philip Yang 2022-01-18 2081 prange->start, prange->last, prange->work_item.op);
367c9b0f1b8750 Philip Yang 2022-01-18 2082
367c9b0f1b8750 Philip Yang 2022-01-18 2083 mm = prange->work_item.mm;
a44fe9ee051aca Felix Kuehling 2021-11-05 2084 retry:
4683cfecadeb38 Philip Yang 2020-04-08 2085 mmap_write_lock(mm);
4683cfecadeb38 Philip Yang 2020-04-08 2086
a0c55ecee10055 Philip Yang 2021-11-16 2087 /* Checking for the need to drain retry faults must be inside
a44fe9ee051aca Felix Kuehling 2021-11-05 2088 * mmap write lock to serialize with munmap notifiers.
4683cfecadeb38 Philip Yang 2020-04-08 2089 */
2e4477282c8cff Philip Yang 2021-11-19 2090 if (unlikely(atomic_read(&svms->drain_pagefaults))) {
a44fe9ee051aca Felix Kuehling 2021-11-05 2091 mmap_write_unlock(mm);
a44fe9ee051aca Felix Kuehling 2021-11-05 2092 svm_range_drain_retry_fault(svms);
a44fe9ee051aca Felix Kuehling 2021-11-05 2093 goto retry;
a44fe9ee051aca Felix Kuehling 2021-11-05 2094 }
a0c55ecee10055 Philip Yang 2021-11-16 2095
367c9b0f1b8750 Philip Yang 2022-01-18 2096 /* Remove from deferred_list must be inside mmap write lock, for
367c9b0f1b8750 Philip Yang 2022-01-18 2097 * two race cases:
367c9b0f1b8750 Philip Yang 2022-01-18 2098 * 1. unmap_from_cpu may change work_item.op and add the range
367c9b0f1b8750 Philip Yang 2022-01-18 2099 * to deferred_list again, cause use after free bug.
367c9b0f1b8750 Philip Yang 2022-01-18 2100 * 2. svm_range_list_lock_and_flush_work may hold mmap write
367c9b0f1b8750 Philip Yang 2022-01-18 2101 * lock and continue because deferred_list is empty, but
367c9b0f1b8750 Philip Yang 2022-01-18 2102 * deferred_list work is actually waiting for mmap lock.
367c9b0f1b8750 Philip Yang 2022-01-18 2103 */
a0c55ecee10055 Philip Yang 2021-11-16 2104 spin_lock(&svms->deferred_list_lock);
4683cfecadeb38 Philip Yang 2020-04-08 2105 list_del_init(&prange->deferred_list);
4683cfecadeb38 Philip Yang 2020-04-08 2106 spin_unlock(&svms->deferred_list_lock);
4683cfecadeb38 Philip Yang 2020-04-08 2107
a0c55ecee10055 Philip Yang 2021-11-16 2108 mutex_lock(&svms->lock);
0b0e518d61af8e Felix Kuehling 2021-02-24 2109 mutex_lock(&prange->migrate_mutex);
4683cfecadeb38 Philip Yang 2020-04-08 2110 while (!list_empty(&prange->child_list)) {
4683cfecadeb38 Philip Yang 2020-04-08 2111 struct svm_range *pchild;
4683cfecadeb38 Philip Yang 2020-04-08 2112
4683cfecadeb38 Philip Yang 2020-04-08 2113 pchild = list_first_entry(&prange->child_list,
4683cfecadeb38 Philip Yang 2020-04-08 2114 struct svm_range, child_list);
4683cfecadeb38 Philip Yang 2020-04-08 2115 pr_debug("child prange 0x%p op %d\n", pchild,
4683cfecadeb38 Philip Yang 2020-04-08 2116 pchild->work_item.op);
4683cfecadeb38 Philip Yang 2020-04-08 2117 list_del_init(&pchild->child_list);
367c9b0f1b8750 Philip Yang 2022-01-18 2118 svm_range_handle_list_op(svms, pchild, mm);
4683cfecadeb38 Philip Yang 2020-04-08 2119 }
0b0e518d61af8e Felix Kuehling 2021-02-24 2120 mutex_unlock(&prange->migrate_mutex);
4683cfecadeb38 Philip Yang 2020-04-08 2121
367c9b0f1b8750 Philip Yang 2022-01-18 2122 svm_range_handle_list_op(svms, prange, mm);
4683cfecadeb38 Philip Yang 2020-04-08 2123 mutex_unlock(&svms->lock);
367c9b0f1b8750 Philip Yang 2022-01-18 2124 mmap_write_unlock(mm);
367c9b0f1b8750 Philip Yang 2022-01-18 2125
367c9b0f1b8750 Philip Yang 2022-01-18 2126 /* Pairs with mmget in svm_range_add_list_work */
367c9b0f1b8750 Philip Yang 2022-01-18 2127 mmput(mm);
4683cfecadeb38 Philip Yang 2020-04-08 2128
4683cfecadeb38 Philip Yang 2020-04-08 2129 spin_lock(&svms->deferred_list_lock);
4683cfecadeb38 Philip Yang 2020-04-08 2130 }
4683cfecadeb38 Philip Yang 2020-04-08 2131 spin_unlock(&svms->deferred_list_lock);
4683cfecadeb38 Philip Yang 2020-04-08 2132 pr_debug("exit svms 0x%p\n", svms);
4683cfecadeb38 Philip Yang 2020-04-08 2133 }
4683cfecadeb38 Philip Yang 2020-04-08 2134
:::::: The code at line 2067 was first introduced by commit
:::::: a0c55ecee10055901c9c1b46d0d129cb6b51fa5d drm/amdkfd: process exit and retry fault race
:::::: TO: Philip Yang <Philip.Yang@xxxxxxx>
:::::: CC: Alex Deucher <alexander.deucher@xxxxxxx>
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@xxxxxxxxxxxx