drm/i915: Avoid reclaim taints from runtime-pm debug

As intel_runtime_pm_get/_put may be called from any blockable context,
we need to avoid allowing reclaim from our mallocs, as we need to
avoid tainting any mutexes held by the callers (as they may themselves
not allow for allocations as they are taken in the shrinker).

<4> [435.339331] WARNING: possible circular locking dependency detected
<4> [435.339364] 5.1.0-rc4-CI-Trybot_4116+ #1 Tainted: G     U
<4> [435.339395] ------------------------------------------------------
<4> [435.339426] gem_caching/1334 is trying to acquire lock:
<4> [435.339456] 000000004505c39b (wakeref#3){+.+.}, at: intel_engine_pm_put+0x1b/0x40 [i915]
<4> [435.339788]
but task is already holding lock:
<4> [435.339819] 00000000ee77b4ed (fs_reclaim){+.+.}, at: fs_reclaim_acquire.part.24+0x0/0x30
<4> [435.339879]
which lock already depends on the new lock.

<4> [435.339918]
the existing dependency chain (in reverse order) is:
<4> [435.339952]
-> #1 (fs_reclaim){+.+.}:
<4> [435.339998]        fs_reclaim_acquire.part.24+0x24/0x30
<4> [435.340035]        kmem_cache_alloc_trace+0x2a/0x290
<4> [435.340311]        __print_intel_runtime_pm_wakeref+0x24/0x160 [i915]
<4> [435.340590]        untrack_intel_runtime_pm_wakeref+0x16e/0x1d0 [i915]
<4> [435.340869]        intel_runtime_pm_put_unchecked+0xd/0x30 [i915]
<4> [435.341147]        __intel_wakeref_put_once+0x22/0x40 [i915]
<4> [435.341508]        i915_request_retire+0x477/0xaf0 [i915]
<4> [435.341871]        ring_retire_requests+0x86/0x160 [i915]
<4> [435.342226]        i915_retire_requests+0x58/0xc0 [i915]
<4> [435.342576]        retire_work_handler+0x5b/0x70 [i915]
<4> [435.342615]        process_one_work+0x245/0x610
<4> [435.342646]        worker_thread+0x37/0x380
<4> [435.342679]        kthread+0x119/0x130
<4> [435.342714]        ret_from_fork+0x3a/0x50
<4> [435.342739]
-> #0 (wakeref#3){+.+.}:
<4> [435.342788]        lock_acquire+0xa6/0x1c0
<4> [435.342822]        __mutex_lock+0x8c/0x960
<4> [435.342853]        atomic_dec_and_mutex_lock+0x33/0x50
<4> [435.343151]        intel_engine_pm_put+0x1b/0x40 [i915]
<4> [435.343501]        i915_request_retire+0x477/0xaf0 [i915]
<4> [435.343851]        ring_retire_requests+0x86/0x160 [i915]
<4> [435.344202]        i915_retire_requests+0x58/0xc0 [i915]
<4> [435.344543]        i915_gem_shrink+0xd8/0x5b0 [i915]
<4> [435.344835]        i915_drop_caches_set+0x17b/0x250 [i915]
<4> [435.344877]        simple_attr_write+0xb0/0xd0
<4> [435.344911]        full_proxy_write+0x51/0x80
<4> [435.344943]        vfs_write+0xbd/0x1b0
<4> [435.344972]        ksys_write+0x55/0xe0
<4> [435.345002]        do_syscall_64+0x55/0x190
<4> [435.345040]        entry_SYSCALL_64_after_hwframe+0x49/0xbe

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190409174108.19396-1-chris@chris-wilson.co.uk

diff --git a/drivers/gpu/drm/i915/intel_runtime_pm.c b/drivers/gpu/drm/i915/intel_runtime_pm.c
index e6d1e592225b511e1bb6b2028da88a31f00a8703..3107a742d8adcef661914d42af9a0e1b0844c5c9 100644 (file)
--- a/drivers/gpu/drm/i915/intel_runtime_pm.c
+++ b/drivers/gpu/drm/i915/intel_runtime_pm.c
@@ -162,7 +162,7 @@ static void cancel_intel_runtime_pm_wakeref(struct drm_i915_private *i915,
                 rpm->debug.count, atomic_read(&rpm->wakeref_count))) {
                char *buf;
 
-               buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+               buf = kmalloc(PAGE_SIZE, GFP_NOWAIT | __GFP_NOWARN);
                if (!buf)
                        return;
 
@@ -198,7 +198,7 @@ __print_intel_runtime_pm_wakeref(struct drm_printer *p,
        unsigned long i;
        char *buf;
 
-       buf = kmalloc(PAGE_SIZE, GFP_KERNEL);
+       buf = kmalloc(PAGE_SIZE, GFP_NOWAIT | __GFP_NOWARN);
        if (!buf)
                return;
 
@@ -282,7 +282,9 @@ void print_intel_runtime_pm_wakeref(struct drm_i915_private *i915,
                if (dbg.count <= alloc)
                        break;
 
-               s = krealloc(dbg.owners, dbg.count * sizeof(*s), GFP_KERNEL);
+               s = krealloc(dbg.owners,
+                            dbg.count * sizeof(*s),
+                            GFP_NOWAIT | __GFP_NOWARN);
                if (!s)
                        goto out;