On Wed, Aug 25, 2021 at 08:23:16PM -0700, Matthew Brost wrote:
Error captures can now be done in a work queue processing G2H messages. These messages need to be completely done being processed in the reset path, to avoid races in the missing G2H cleanup, which create a dependency on memory allocations and dma fences (i915_requests). Requests depend on resets, thus now we have a circular dependency. To work around this, allocate the error capture in a nowait context.
For completeness Daniel suggested we include the lockdep splat, included below:
[ 154.625989] ====================================================== [ 154.632195] WARNING: possible circular locking dependency detected [ 154.638393] 5.14.0-rc5-guc+ #50 Tainted: G U [ 154.643991] ------------------------------------------------------ [ 154.650196] i915_selftest/1673 is trying to acquire lock: [ 154.655621] ffff8881079cb918 ((work_completion)(&ct->requests.worker)){+.+.}-{0:0}, at: __flush_work+0x350/0x4d0 [ 154.665826] but task is already holding lock: [ 154.671682] ffff8881079cbfb8 (>->reset.mutex){+.+.}-{3:3}, at: intel_gt_reset+0xf0/0x300 [i915] [ 154.680659] which lock already depends on the new lock.
[ 154.688857] the existing dependency chain (in reverse order) is: [ 154.696365] -> #2 (>->reset.mutex){+.+.}-{3:3}: [ 154.702571] lock_acquire+0xd2/0x300 [ 154.706695] i915_gem_shrinker_taints_mutex+0x2d/0x50 [i915] [ 154.712959] intel_gt_init_reset+0x61/0x80 [i915] [ 154.718258] intel_gt_init_early+0xe6/0x120 [i915] [ 154.723648] i915_driver_probe+0x592/0xdc0 [i915] [ 154.728942] i915_pci_probe+0x43/0x1c0 [i915] [ 154.733891] pci_device_probe+0x9b/0x110 [ 154.738362] really_probe+0x1a6/0x3a0 [ 154.742568] __driver_probe_device+0xf9/0x170 [ 154.747468] driver_probe_device+0x19/0x90 [ 154.752114] __driver_attach+0x99/0x170 [ 154.756492] bus_for_each_dev+0x73/0xc0 [ 154.760870] bus_add_driver+0x14b/0x1f0 [ 154.765248] driver_register+0x67/0xb0 [ 154.769542] i915_init+0x18/0x8c [i915] [ 154.773964] do_one_initcall+0x53/0x2e0 [ 154.778343] do_init_module+0x56/0x210 [ 154.782639] load_module+0x25fc/0x29f0 [ 154.786934] __do_sys_finit_module+0xae/0x110 [ 154.791835] do_syscall_64+0x38/0xc0 [ 154.795958] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 154.801558] -> #1 (fs_reclaim){+.+.}-{0:0}: [ 154.807241] lock_acquire+0xd2/0x300 [ 154.811361] fs_reclaim_acquire+0x9e/0xd0 [ 154.815914] kmem_cache_alloc_trace+0x30/0x790 [ 154.820899] i915_gpu_coredump_alloc+0x53/0x1a0 [i915] [ 154.826649] i915_gpu_coredump+0x39/0x560 [i915] [ 154.831866] i915_capture_error_state+0xa/0x70 [i915] [ 154.837513] intel_guc_context_reset_process_msg+0x174/0x1f0 [i915] [ 154.844383] ct_incoming_request_worker_func+0x130/0x1b0 [i915] [ 154.850898] process_one_work+0x264/0x590 [ 154.855451] worker_thread+0x4b/0x3a0 [ 154.859655] kthread+0x147/0x170 [ 154.863428] ret_from_fork+0x1f/0x30 [ 154.867548] -> #0 ((work_completion)(&ct->requests.worker)){+.+.}-{0:0}: [ 154.875747] check_prev_add+0x90/0xc30 [ 154.880042] __lock_acquire+0x1643/0x2110 [ 154.884595] lock_acquire+0xd2/0x300 [ 154.888715] __flush_work+0x373/0x4d0 [ 154.892920] intel_guc_submission_reset_prepare+0xf3/0x340 [i915] [ 154.899606] intel_uc_reset_prepare+0x40/0x50 [i915] [ 154.905166] reset_prepare+0x55/0x60 [i915] [ 154.909946] intel_gt_reset+0x11c/0x300 [i915] [ 154.914984] do_device_reset+0x13/0x20 [i915] [ 154.919936] check_whitelist_across_reset+0x166/0x250 [i915] [ 154.926212] live_reset_whitelist.cold+0x6a/0x7a [i915] [ 154.932037] __i915_subtests.cold+0x20/0x74 [i915] [ 154.937428] __run_selftests.cold+0x96/0xee [i915] [ 154.942816] i915_live_selftests+0x2c/0x60 [i915] [ 154.948125] i915_pci_probe+0x93/0x1c0 [i915] [ 154.953076] pci_device_probe+0x9b/0x110 [ 154.957545] really_probe+0x1a6/0x3a0 [ 154.961749] __driver_probe_device+0xf9/0x170 [ 154.966653] driver_probe_device+0x19/0x90 [ 154.971290] __driver_attach+0x99/0x170 [ 154.975671] bus_for_each_dev+0x73/0xc0 [ 154.980053] bus_add_driver+0x14b/0x1f0 [ 154.984431] driver_register+0x67/0xb0 [ 154.988725] i915_init+0x18/0x8c [i915] [ 154.993149] do_one_initcall+0x53/0x2e0 [ 154.997527] do_init_module+0x56/0x210 [ 155.001822] load_module+0x25fc/0x29f0 [ 155.006118] __do_sys_finit_module+0xae/0x110 [ 155.011019] do_syscall_64+0x38/0xc0 [ 155.015139] entry_SYSCALL_64_after_hwframe+0x44/0xae [ 155.020729] other info that might help us debug this:
[ 155.028752] Chain exists of: (work_completion)(&ct->requests.worker) --> fs_reclaim --> >->reset.mutex
[ 155.041294] Possible unsafe locking scenario:
[ 155.047240] CPU0 CPU1 [ 155.051791] ---- ---- [ 155.056344] lock(>->reset.mutex); [ 155.060026] lock(fs_reclaim); [ 155.065706] lock(>->reset.mutex); [ 155.071912] lock((work_completion)(&ct->requests.worker)); [ 155.077595] *** DEADLOCK ***
v2: (Daniel Vetter)
- Use GFP_NOWAIT instead GFP_ATOMIC
Fixes: dc0dad365c5e ("Fix for error capture after full GPU reset with GuC") Fixes: 573ba126aef3 ("Capture error state on context reset") Signed-off-by: Matthew Brost matthew.brost@intel.com
drivers/gpu/drm/i915/i915_gpu_error.c | 39 +++++++++++++-------------- 1 file changed, 19 insertions(+), 20 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c index b9f66dbd46bb..8696ead02118 100644 --- a/drivers/gpu/drm/i915/i915_gpu_error.c +++ b/drivers/gpu/drm/i915/i915_gpu_error.c @@ -49,8 +49,7 @@ #include "i915_memcpy.h" #include "i915_scatterlist.h"
-#define ALLOW_FAIL (GFP_KERNEL | __GFP_RETRY_MAYFAIL | __GFP_NOWARN) -#define ATOMIC_MAYFAIL (GFP_ATOMIC | __GFP_NOWARN) +#define ATOMIC_MAYFAIL (GFP_NOWAIT | __GFP_NOWARN)
static void __sg_set_buf(struct scatterlist *sg, void *addr, unsigned int len, loff_t it) @@ -79,7 +78,7 @@ static bool __i915_error_grow(struct drm_i915_error_state_buf *e, size_t len) if (e->cur == e->end) { struct scatterlist *sgl;
sgl = (typeof(sgl))__get_free_page(ALLOW_FAIL);
sgl = (typeof(sgl))__get_free_page(ATOMIC_MAYFAIL);@@ -99,10 +98,10 @@ static bool __i915_error_grow(struct drm_i915_error_state_buf *e, size_t len) }
e->size = ALIGN(len + 1, SZ_64K);
- e->buf = kmalloc(e->size, ALLOW_FAIL);
- e->buf = kmalloc(e->size, ATOMIC_MAYFAIL); if (!e->buf) { e->size = PAGE_ALIGN(len + 1);
e->buf = kmalloc(e->size, GFP_KERNEL);
e->buf = kmalloc(e->size, ATOMIC_MAYFAIL);@@ -243,12 +242,12 @@ static bool compress_init(struct i915_vma_compress *c) { struct z_stream_s *zstream = &c->zstream;
- if (pool_init(&c->pool, ALLOW_FAIL))
if (pool_init(&c->pool, ATOMIC_MAYFAIL)) return false;
zstream->workspace = kmalloc(zlib_deflate_workspacesize(MAX_WBITS, MAX_MEM_LEVEL),
ALLOW_FAIL);
ATOMIC_MAYFAIL);@@ -256,7 +255,7 @@ static bool compress_init(struct i915_vma_compress *c)
c->tmp = NULL; if (i915_has_memcpy_from_wc())
c->tmp = pool_alloc(&c->pool, ALLOW_FAIL);
c->tmp = pool_alloc(&c->pool, ATOMIC_MAYFAIL);return true;
} @@ -280,7 +279,7 @@ static void *compress_next_page(struct i915_vma_compress *c, if (dst->page_count >= dst->num_pages) return ERR_PTR(-ENOSPC);
- page = pool_alloc(&c->pool, ALLOW_FAIL);
- page = pool_alloc(&c->pool, ATOMIC_MAYFAIL); if (!page) return ERR_PTR(-ENOMEM);
@@ -376,7 +375,7 @@ struct i915_vma_compress {
static bool compress_init(struct i915_vma_compress *c) {
- return pool_init(&c->pool, ALLOW_FAIL) == 0;
- return pool_init(&c->pool, ATOMIC_MAYFAIL) == 0;
}
static bool compress_start(struct i915_vma_compress *c) @@ -391,7 +390,7 @@ static int compress_page(struct i915_vma_compress *c, { void *ptr;
- ptr = pool_alloc(&c->pool, ALLOW_FAIL);
- ptr = pool_alloc(&c->pool, ATOMIC_MAYFAIL); if (!ptr) return -ENOMEM;
@@ -1026,7 +1025,7 @@ i915_vma_coredump_create(const struct intel_gt *gt,
num_pages = min_t(u64, vma->size, vma->obj->base.size) >> PAGE_SHIFT; num_pages = DIV_ROUND_UP(10 * num_pages, 8); /* worstcase zlib growth */
- dst = kmalloc(sizeof(*dst) + num_pages * sizeof(u32 *), ALLOW_FAIL);
- dst = kmalloc(sizeof(*dst) + num_pages * sizeof(u32 *), ATOMIC_MAYFAIL); if (!dst) return NULL;
@@ -1462,7 +1461,7 @@ capture_engine(struct intel_engine_cs *engine, struct i915_request *rq = NULL; unsigned long flags;
- ee = intel_engine_coredump_alloc(engine, GFP_KERNEL);
- ee = intel_engine_coredump_alloc(engine, ATOMIC_MAYFAIL); if (!ee) return NULL;
@@ -1510,7 +1509,7 @@ gt_record_engines(struct intel_gt_coredump *gt, struct intel_engine_coredump *ee;
/* Refill our page pool before entering atomic section */
pool_refill(&compress->pool, ALLOW_FAIL);
pool_refill(&compress->pool, ATOMIC_MAYFAIL);ee = capture_engine(engine, compress); if (!ee)
@@ -1536,7 +1535,7 @@ gt_record_uc(struct intel_gt_coredump *gt, const struct intel_uc *uc = >->_gt->uc; struct intel_uc_coredump *error_uc;
- error_uc = kzalloc(sizeof(*error_uc), ALLOW_FAIL);
- error_uc = kzalloc(sizeof(*error_uc), ATOMIC_MAYFAIL); if (!error_uc) return NULL;
@@ -1547,8 +1546,8 @@ gt_record_uc(struct intel_gt_coredump *gt, * As modparams are generally accesible from the userspace make * explicit copies of the firmware paths. */
- error_uc->guc_fw.path = kstrdup(uc->guc.fw.path, ALLOW_FAIL);
- error_uc->huc_fw.path = kstrdup(uc->huc.fw.path, ALLOW_FAIL);
- error_uc->guc_fw.path = kstrdup(uc->guc.fw.path, ATOMIC_MAYFAIL);
- error_uc->huc_fw.path = kstrdup(uc->huc.fw.path, ATOMIC_MAYFAIL); error_uc->guc_log = i915_vma_coredump_create(gt->_gt, uc->guc.log.vma, "GuC log buffer",
@@ -1815,7 +1814,7 @@ i915_vma_capture_prepare(struct intel_gt_coredump *gt) { struct i915_vma_compress *compress;
- compress = kmalloc(sizeof(*compress), ALLOW_FAIL);
- compress = kmalloc(sizeof(*compress), ATOMIC_MAYFAIL); if (!compress) return NULL;
@@ -1848,11 +1847,11 @@ i915_gpu_coredump(struct intel_gt *gt, intel_engine_mask_t engine_mask) if (IS_ERR(error)) return error;
- error = i915_gpu_coredump_alloc(i915, ALLOW_FAIL);
- error = i915_gpu_coredump_alloc(i915, ATOMIC_MAYFAIL); if (!error) return ERR_PTR(-ENOMEM);
- error->gt = intel_gt_coredump_alloc(gt, ALLOW_FAIL);
- error->gt = intel_gt_coredump_alloc(gt, ATOMIC_MAYFAIL); if (error->gt) { struct i915_vma_compress *compress;
-- 2.32.0