[RFC PATCH v3 05/11] drm, cgroup: Add peak GEM buffer allocation limit

[Kenny Ho]

drm.buffer.peak.stats
        A read-only flat-keyed file which exists on all cgroups.  Each
        entry is keyed by the drm device's major:minor.

        Largest GEM buffer allocated in bytes.

drm.buffer.peak.default
        A read-only flat-keyed file which exists on the root cgroup.
        Each entry is keyed by the drm device's major:minor.

        Default limits on the largest GEM buffer allocation in bytes.

drm.buffer.peak.max
        A read-write flat-keyed file which exists on all cgroups.  Each
        entry is keyed by the drm device's major:minor.

        Per device limits on the largest GEM buffer allocation in bytes.
        This is a hard limit.  Attempts in allocating beyond the cgroup
        limit will result in ENOMEM.  Shorthand understood by memparse
        (such as k, m, g) can be used.

        Set largest allocation for /dev/dri/card1 to 4MB
        echo "226:1 4m" > drm.buffer.peak.max

Change-Id: I0830d56775568e1cf215b56cc892d5e7945e9f25
Signed-off-by: Kenny Ho <Kenny.Ho at amd.com>
---
 include/linux/cgroup_drm.h |  3 ++
 kernel/cgroup/drm.c        | 61 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 64 insertions(+)

diff --git a/include/linux/cgroup_drm.h b/include/linux/cgroup_drm.h
index efa019666f1c..126c156ffd70 100644
--- a/include/linux/cgroup_drm.h
+++ b/include/linux/cgroup_drm.h
@@ -17,6 +17,9 @@ struct drmcgrp_device_resource {
 	/* for per device stats */
 	s64			bo_stats_total_allocated;
 	s64			bo_limits_total_allocated;
+
+	size_t			bo_stats_peak_allocated;
+	size_t			bo_limits_peak_allocated;
 };
 
 struct drmcgrp {
diff --git a/kernel/cgroup/drm.c b/kernel/cgroup/drm.c
index cfc1fe74dca3..265008197654 100644
--- a/kernel/cgroup/drm.c
+++ b/kernel/cgroup/drm.c
@@ -19,6 +19,7 @@ struct drmcgrp_device {
 	struct mutex		mutex;
 
 	s64			bo_limits_total_allocated_default;
+	size_t			bo_limits_peak_allocated_default;
 };
 
 #define DRMCG_CTF_PRIV_SIZE 3
@@ -31,6 +32,7 @@ struct drmcgrp_device {
 
 enum drmcgrp_res_type {
 	DRMCGRP_TYPE_BO_TOTAL,
+	DRMCGRP_TYPE_BO_PEAK,
 };
 
 enum drmcgrp_file_type {
@@ -78,6 +80,9 @@ static inline int init_drmcgrp_single(struct drmcgrp *drmcgrp, int minor)
 	if (known_drmcgrp_devs[minor] != NULL) {
 		ddr->bo_limits_total_allocated =
 		  known_drmcgrp_devs[minor]->bo_limits_total_allocated_default;
+
+		ddr->bo_limits_peak_allocated =
+		  known_drmcgrp_devs[minor]->bo_limits_peak_allocated_default;
 	}
 
 	return 0;
@@ -137,6 +142,9 @@ static inline void drmcgrp_print_stats(struct drmcgrp_device_resource *ddr,
 	case DRMCGRP_TYPE_BO_TOTAL:
 		seq_printf(sf, "%lld\n", ddr->bo_stats_total_allocated);
 		break;
+	case DRMCGRP_TYPE_BO_PEAK:
+		seq_printf(sf, "%zu\n", ddr->bo_stats_peak_allocated);
+		break;
 	default:
 		seq_puts(sf, "\n");
 		break;
@@ -155,6 +163,9 @@ static inline void drmcgrp_print_limits(struct drmcgrp_device_resource *ddr,
 	case DRMCGRP_TYPE_BO_TOTAL:
 		seq_printf(sf, "%lld\n", ddr->bo_limits_total_allocated);
 		break;
+	case DRMCGRP_TYPE_BO_PEAK:
+		seq_printf(sf, "%zu\n", ddr->bo_limits_peak_allocated);
+		break;
 	default:
 		seq_puts(sf, "\n");
 		break;
@@ -174,6 +185,10 @@ static inline void drmcgrp_print_default(struct drmcgrp_device *ddev,
 		seq_printf(sf, "%lld\n",
 				ddev->bo_limits_total_allocated_default);
 		break;
+	case DRMCGRP_TYPE_BO_PEAK:
+		seq_printf(sf, "%zu\n",
+				ddev->bo_limits_peak_allocated_default);
+		break;
 	default:
 		seq_puts(sf, "\n");
 		break;
@@ -315,6 +330,23 @@ ssize_t drmcgrp_bo_limit_write(struct kernfs_open_file *of, char *buf,
 
 			ddr->bo_limits_total_allocated = val;
 			break;
+		case DRMCGRP_TYPE_BO_PEAK:
+			p_max = parent == NULL ? SIZE_MAX :
+				parent->dev_resources[minor]->
+				bo_limits_peak_allocated;
+
+			rc = drmcgrp_process_limit_val(sattr, true,
+				ddev->bo_limits_peak_allocated_default,
+				p_max,
+				&val);
+
+			if (rc || val < 0) {
+				drmcgrp_pr_cft_err(drmcgrp, cft_name, minor);
+				continue;
+			}
+
+			ddr->bo_limits_peak_allocated = val;
+			break;
 		default:
 			break;
 		}
@@ -344,6 +376,26 @@ struct cftype files[] = {
 		.private = DRMCG_CTF_PRIV(DRMCGRP_TYPE_BO_TOTAL,
 						DRMCGRP_FTYPE_LIMIT),
 	},
+	{
+		.name = "buffer.peak.stats",
+		.seq_show = drmcgrp_bo_show,
+		.private = DRMCG_CTF_PRIV(DRMCGRP_TYPE_BO_PEAK,
+						DRMCGRP_FTYPE_STATS),
+	},
+	{
+		.name = "buffer.peak.default",
+		.seq_show = drmcgrp_bo_show,
+		.flags = CFTYPE_ONLY_ON_ROOT,
+		.private = DRMCG_CTF_PRIV(DRMCGRP_TYPE_BO_PEAK,
+						DRMCGRP_FTYPE_DEFAULT),
+	},
+	{
+		.name = "buffer.peak.max",
+		.write = drmcgrp_bo_limit_write,
+		.seq_show = drmcgrp_bo_show,
+		.private = DRMCG_CTF_PRIV(DRMCGRP_TYPE_BO_PEAK,
+						DRMCGRP_FTYPE_LIMIT),
+	},
 	{ }	/* terminate */
 };
 
@@ -365,6 +417,7 @@ int drmcgrp_register_device(struct drm_device *dev)
 
 	ddev->dev = dev;
 	ddev->bo_limits_total_allocated_default = S64_MAX;
+	ddev->bo_limits_peak_allocated_default = SIZE_MAX;
 
 	mutex_init(&ddev->mutex);
 
@@ -436,6 +489,11 @@ bool drmcgrp_bo_can_allocate(struct task_struct *task, struct drm_device *dev,
 			result = false;
 			break;
 		}
+
+		if (d->bo_limits_peak_allocated < size) {
+			result = false;
+			break;
+		}
 	}
 	mutex_unlock(&known_drmcgrp_devs[devIdx]->mutex);
 
@@ -457,6 +515,9 @@ void drmcgrp_chg_bo_alloc(struct drmcgrp *drmcgrp, struct drm_device *dev,
 		ddr = drmcgrp->dev_resources[devIdx];
 
 		ddr->bo_stats_total_allocated += (s64)size;
+
+		if (ddr->bo_stats_peak_allocated < (size_t)size)
+			ddr->bo_stats_peak_allocated = (size_t)size;
 	}
 	mutex_unlock(&known_drmcgrp_devs[devIdx]->mutex);
 }
-- 
2.21.0