Hi Tvrtko, Thanks for review. On Wednesday, 14 September 2022 17:37:19 CEST Tvrtko Ursulin wrote: > > On 13/09/2022 17:10, Janusz Krzysztofik wrote: > > From: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > > > i915_perf assumes that it can use the i915_gem_context reference to > > protect its i915->gem.contexts.list iteration. However, this requires > > that we do not remove the context from the list until after we drop the > > final reference and release the struct. If, as currently, we remove the > > context from the list during context_close(), the link.next pointer may > > be poisoned while we are holding the context reference and cause a GPF: > > > > [ 4070.573157] i915 0000:00:02.0: [drm:i915_perf_open_ioctl [i915]] filtering on ctx_id=0x1fffff ctx_id_mask=0x1fffff > > [ 4070.574881] general protection fault, probably for non-canonical address 0xdead000000000100: 0000 [#1] PREEMPT SMP > > [ 4070.574897] CPU: 1 PID: 284392 Comm: amd_performance Tainted: G E 5.17.9 #180 > > [ 4070.574903] Hardware name: Intel Corporation NUC7i5BNK/NUC7i5BNB, BIOS BNKBL357.86A.0052.2017.0918.1346 09/18/2017 > > [ 4070.574907] RIP: 0010:oa_configure_all_contexts.isra.0+0x222/0x350 [i915] > > [ 4070.574982] Code: 08 e8 32 6e 10 e1 4d 8b 6d 50 b8 ff ff ff ff 49 83 ed 50 f0 41 0f c1 04 24 83 f8 01 0f 84 e3 00 00 00 85 c0 0f 8e fa 00 00 00 <49> 8b 45 50 48 8d 70 b0 49 8d 45 50 48 39 44 24 10 0f 85 34 fe ff > > [ 4070.574990] RSP: 0018:ffffc90002077b78 EFLAGS: 00010202 > > [ 4070.574995] RAX: 0000000000000002 RBX: 0000000000000002 RCX: 0000000000000000 > > [ 4070.575000] RDX: 0000000000000001 RSI: ffffc90002077b20 RDI: ffff88810ddc7c68 > > [ 4070.575004] RBP: 0000000000000001 R08: ffff888103242648 R09: fffffffffffffffc > > [ 4070.575008] R10: ffffffff82c50bc0 R11: 0000000000025c80 R12: ffff888101bf1860 > > [ 4070.575012] R13: dead0000000000b0 R14: ffffc90002077c04 R15: ffff88810be5cabc > > [ 4070.575016] FS: 00007f1ed50c0780(0000) GS:ffff88885ec80000(0000) knlGS:0000000000000000 > > [ 4070.575021] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 4070.575025] CR2: 00007f1ed5590280 CR3: 000000010ef6f005 CR4: 00000000003706e0 > > [ 4070.575029] Call Trace: > > [ 4070.575033] <TASK> > > [ 4070.575037] lrc_configure_all_contexts+0x13e/0x150 [i915] > > [ 4070.575103] gen8_enable_metric_set+0x4d/0x90 [i915] > > [ 4070.575164] i915_perf_open_ioctl+0xbc0/0x1500 [i915] > > [ 4070.575224] ? asm_common_interrupt+0x1e/0x40 > > [ 4070.575232] ? i915_oa_init_reg_state+0x110/0x110 [i915] > > [ 4070.575290] drm_ioctl_kernel+0x85/0x110 > > [ 4070.575296] ? update_load_avg+0x5f/0x5e0 > > [ 4070.575302] drm_ioctl+0x1d3/0x370 > > [ 4070.575307] ? i915_oa_init_reg_state+0x110/0x110 [i915] > > [ 4070.575382] ? gen8_gt_irq_handler+0x46/0x130 [i915] > > [ 4070.575445] __x64_sys_ioctl+0x3c4/0x8d0 > > [ 4070.575451] ? __do_softirq+0xaa/0x1d2 > > [ 4070.575456] do_syscall_64+0x35/0x80 > > [ 4070.575461] entry_SYSCALL_64_after_hwframe+0x44/0xae > > [ 4070.575467] RIP: 0033:0x7f1ed5c10397 > > [ 4070.575471] Code: 3c 1c e8 1c ff ff ff 85 c0 79 87 49 c7 c4 ff ff ff ff 5b 5d 4c 89 e0 41 5c c3 66 0f 1f 84 00 00 00 00 00 b8 10 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d a9 da 0d 00 f7 d8 64 89 01 48 > > [ 4070.575478] RSP: 002b:00007ffd65c8d7a8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > > [ 4070.575484] RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 00007f1ed5c10397 > > [ 4070.575488] RDX: 00007ffd65c8d7c0 RSI: 0000000040106476 RDI: 0000000000000006 > > [ 4070.575492] RBP: 00005620972f9c60 R08: 000000000000000a R09: 0000000000000005 > > [ 4070.575496] R10: 000000000000000d R11: 0000000000000246 R12: 000000000000000a > > [ 4070.575500] R13: 000000000000000d R14: 0000000000000000 R15: 00007ffd65c8d7c0 > > [ 4070.575505] </TASK> > > [ 4070.575507] Modules linked in: nls_ascii(E) nls_cp437(E) vfat(E) fat(E) i915(E) x86_pkg_temp_thermal(E) intel_powerclamp(E) crct10dif_pclmul(E) crc32_pclmul(E) crc32c_intel(E) aesni_intel(E) crypto_simd(E) intel_gtt(E) cryptd(E) ttm(E) rapl(E) intel_cstate(E) drm_kms_helper(E) cfbfillrect(E) syscopyarea(E) cfbimgblt(E) intel_uncore(E) sysfillrect(E) mei_me(E) sysimgblt(E) i2c_i801(E) fb_sys_fops(E) mei(E) intel_pch_thermal(E) i2c_smbus(E) cfbcopyarea(E) video(E) button(E) efivarfs(E) autofs4(E) > > [ 4070.575549] ---[ end trace 0000000000000000 ]--- > > > > Reported-by: Mark Janes <mark.janes@xxxxxxxxx> > > Closes: https://gitlab.freedesktop.org/drm/intel/issues/6222 > > References: a4e7ccdac38e ("drm/i915: Move context management under GEM") > > Fixes: f8246cf4d9a9 ("drm/i915/gem: Drop free_work for GEM contexts") > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > Reviewed-by: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx> > > Signed-off-by: Andi Shyti <andi.shyti@xxxxxxxxxxxxxxx> > > Signed-off-by: Janusz Krzysztofik <janusz.krzysztofik@xxxxxxxxxxxxxxx> > > Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > > Cc: <stable@xxxxxxxxxxxxxxx> # v5.12+ > > --- > > drivers/gpu/drm/i915/gem/i915_gem_context.c | 14 +++++++------- > > drivers/gpu/drm/i915/i915_perf.c | 18 ++++++++++-------- > > drivers/gpu/drm/i915/i915_sysfs.c | 8 ++++---- > > 3 files changed, 21 insertions(+), 19 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c > > index dabdfe09f5e51..9d7142ab63c05 100644 > > --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c > > +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c > > @@ -1133,7 +1133,6 @@ static struct i915_gem_engines *default_engines(struct i915_gem_context *ctx, > > err = ERR_PTR(ret); > > goto free_engines; > > } > > - > > Best avoid unrelated cleanups especially when there is a fixes tag. Sure, I'll drop this. > > > } > > > > return e; > > @@ -1265,10 +1264,15 @@ static void i915_gem_context_release_work(struct work_struct *work) > > struct i915_gem_context *ctx = container_of(work, typeof(*ctx), > > release_work); > > struct i915_address_space *vm; > > + unsigned long flags; > > > > trace_i915_context_free(ctx); > > GEM_BUG_ON(!i915_gem_context_is_closed(ctx)); > > > > + spin_lock_irqsave(&ctx->i915->gem.contexts.lock, flags); > > Why irqsave and the conversion to irq safe elsewhere? Worker context > does not require it and I don't see the connection to the change of > list_del location. Yes, please let me revisit all those spin_locks on i915->gem.contexts.lock then and reconsider which variants are most optimal for use in those several different places we need them. Thanks, Janusz > > Regards, > > Tvrtko > > > + list_del(&ctx->link); > > + spin_unlock_irqrestore(&ctx->i915->gem.contexts.lock, flags); > > + > > if (ctx->syncobj) > > drm_syncobj_put(ctx->syncobj); > > > > @@ -1521,10 +1525,6 @@ static void context_close(struct i915_gem_context *ctx) > > > > ctx->file_priv = ERR_PTR(-EBADF); > > > > - spin_lock(&ctx->i915->gem.contexts.lock); > > - list_del(&ctx->link); > > - spin_unlock(&ctx->i915->gem.contexts.lock); > > - > > client = ctx->client; > > if (client) { > > spin_lock(&client->ctx_lock); > > @@ -1717,9 +1717,9 @@ static void gem_context_register(struct i915_gem_context *ctx, > > list_add_tail_rcu(&ctx->client_link, &ctx->client->ctx_list); > > spin_unlock(&ctx->client->ctx_lock); > > > > - spin_lock(&i915->gem.contexts.lock); > > + spin_lock_irq(&i915->gem.contexts.lock); > > list_add_tail(&ctx->link, &i915->gem.contexts.list); > > - spin_unlock(&i915->gem.contexts.lock); > > + spin_unlock_irq(&i915->gem.contexts.lock); > > } > > > > int i915_gem_context_open(struct drm_i915_private *i915, > > diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c > > index f3c23fe9ad9ce..83bb71466f8f0 100644 > > --- a/drivers/gpu/drm/i915/i915_perf.c > > +++ b/drivers/gpu/drm/i915/i915_perf.c > > @@ -2379,24 +2379,26 @@ oa_configure_all_contexts(struct i915_perf_stream *stream, > > * context. Contexts idle at the time of reconfiguration are not > > * trapped behind the barrier. > > */ > > - spin_lock(&i915->gem.contexts.lock); > > + spin_lock_irq(&i915->gem.contexts.lock); > > list_for_each_entry_safe(ctx, cn, &i915->gem.contexts.list, link) { > > if (!kref_get_unless_zero(&ctx->ref)) > > continue; > > > > - spin_unlock(&i915->gem.contexts.lock); > > + spin_unlock_irq(&i915->gem.contexts.lock); > > > > - err = gen8_configure_context(ctx, regs, num_regs); > > - if (err) { > > - i915_gem_context_put(ctx); > > - return err; > > + if (!i915_gem_context_is_closed(ctx)) { > > + err = gen8_configure_context(ctx, regs, num_regs); > > + if (err) { > > + i915_gem_context_put(ctx); > > + return err; > > + } > > } > > > > - spin_lock(&i915->gem.contexts.lock); > > + spin_lock_irq(&i915->gem.contexts.lock); > > list_safe_reset_next(ctx, cn, link); > > i915_gem_context_put(ctx); > > } > > - spin_unlock(&i915->gem.contexts.lock); > > + spin_unlock_irq(&i915->gem.contexts.lock); > > > > /* > > * After updating all other contexts, we need to modify ourselves. > > diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c > > index 1e27502108313..40c7671fc0591 100644 > > --- a/drivers/gpu/drm/i915/i915_sysfs.c > > +++ b/drivers/gpu/drm/i915/i915_sysfs.c > > @@ -77,12 +77,12 @@ i915_l3_read(struct file *filp, struct kobject *kobj, > > count = min_t(size_t, GEN7_L3LOG_SIZE - offset, count); > > memset(buf, 0, count); > > > > - spin_lock(&i915->gem.contexts.lock); > > + spin_lock_irq(&i915->gem.contexts.lock); > > if (i915->l3_parity.remap_info[slice]) > > memcpy(buf, > > i915->l3_parity.remap_info[slice] + offset / sizeof(u32), > > count); > > - spin_unlock(&i915->gem.contexts.lock); > > + spin_unlock_irq(&i915->gem.contexts.lock); > > > > return count; > > } > > @@ -110,7 +110,7 @@ i915_l3_write(struct file *filp, struct kobject *kobj, > > if (!remap_info) > > return -ENOMEM; > > > > - spin_lock(&i915->gem.contexts.lock); > > + spin_lock_irq(&i915->gem.contexts.lock); > > > > if (i915->l3_parity.remap_info[slice]) { > > freeme = remap_info; > > @@ -126,7 +126,7 @@ i915_l3_write(struct file *filp, struct kobject *kobj, > > list_for_each_entry(ctx, &i915->gem.contexts.list, link) > > ctx->remap_slice |= BIT(slice); > > > > - spin_unlock(&i915->gem.contexts.lock); > > + spin_unlock_irq(&i915->gem.contexts.lock); > > kfree(freeme); > > > > /* >
