New subject: 4.19-stable: Re: [PATCH 2/3] drm/i915: Break up error capture compression loops with cond_resched()

16 Sep 2020

As the error capture will compress user buffers as directed to by the
user, it can take an arbitrary amount of time and space. Break up the
compression loops with a call to cond_resched(), that will allow other
processes to schedule (avoiding the soft lockups) and also serve as a
warning should we try to make this loop atomic in the future.
Signed-off-by: Chris Wilson chris@chris-wilson.co.uk
Cc: Mika Kuoppala mika.kuoppala@linux.intel.com
Cc: stable@vger.kernel.org
Reviewed-by: Mika Kuoppala mika.kuoppala@linux.intel.com
---
 drivers/gpu/drm/i915/i915_gpu_error.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_gpu_error.c b/drivers/gpu/drm/i915/i915_gpu_error.c
index 3e6cbb0d1150..a635ec8d0b94 100644
--- a/drivers/gpu/drm/i915/i915_gpu_error.c
+++ b/drivers/gpu/drm/i915/i915_gpu_error.c
@@ -311,6 +311,8 @@ static int compress_page(struct i915_vma_compress *c,
if (zlib_deflate(zstream, Z_NO_FLUSH) != Z_OK)
    		return -EIO;
+
+		cond_resched();
    } while (zstream->avail_in);
/* Fallback to uncompressed if we increase size? */
@@ -397,6 +399,7 @@ static int compress_page(struct i915_vma_compress *c,
    if (!(wc && i915_memcpy_from_wc(ptr, src, PAGE_SIZE)))
    	memcpy(ptr, src, PAGE_SIZE);
    dst->pages[dst->page_count++] = ptr;
+	cond_resched();
return 0;
 }
-- 
2.20.1


    