[PATCH v2 2/3] drm/panthor: Implement evicted status for GEM objects
From: Nicolas Frattaroli
Date: Tue Apr 21 2026 - 06:49:58 EST
For fdinfo to be able to fill its evicted counter with data, panthor
needs to keep track of whether a GEM object has ever been reclaimed.
Just checking whether the pages are resident isn't enough, as newly
allocated objects also won't be resident.
Do this with a new atomic_t member on panthor_gem_object. It's increased
when an object gets evicted by the shrinker, and saturates at INT_MAX.
This means that once an object has been evicted at least once, its
reclaim counter will never return to 0.
Due to this, it's possible to distinguish evicted non-resident pages
from newly allocated non-resident pages by checking whether
reclaimed_count is != 0
Use this new member to then set the appropriate DRM_GEM_OBJECT_EVICTED
status flag for fdinfo.
Also add a new column and status flag to the panthor gems debugfs: the
column is the number of times an object has been evicted, whereas the
flag indicates whether it currently is evicted.
Signed-off-by: Nicolas Frattaroli <nicolas.frattaroli@xxxxxxxxxxxxx>
---
drivers/gpu/drm/panthor/panthor_gem.c | 18 ++++++++++++++----
drivers/gpu/drm/panthor/panthor_gem.h | 10 ++++++++++
2 files changed, 24 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c
index 69cef05b6ef7..b6fe20b7e6d0 100644
--- a/drivers/gpu/drm/panthor/panthor_gem.c
+++ b/drivers/gpu/drm/panthor/panthor_gem.c
@@ -687,6 +687,8 @@ static void panthor_gem_evict_locked(struct panthor_gem_object *bo)
if (drm_WARN_ON_ONCE(bo->base.dev, !bo->backing.pages))
return;
+ atomic_add_unless(&bo->reclaimed_count, 1, INT_MAX);
+
panthor_gem_dev_map_cleanup_locked(bo);
panthor_gem_backing_cleanup_locked(bo);
panthor_gem_update_reclaim_state_locked(bo, NULL);
@@ -788,6 +790,8 @@ static enum drm_gem_object_status panthor_gem_status(struct drm_gem_object *obj)
if (drm_gem_is_imported(&bo->base) || bo->backing.pages)
res |= DRM_GEM_OBJECT_RESIDENT;
+ else if (atomic_read(&bo->reclaimed_count))
+ res |= DRM_GEM_OBJECT_EVICTED;
return res;
}
@@ -1595,6 +1599,7 @@ static void panthor_gem_debugfs_print_flag_names(struct seq_file *m)
static const char * const gem_state_flags_names[] = {
[PANTHOR_DEBUGFS_GEM_STATE_IMPORTED_BIT] = "imported",
[PANTHOR_DEBUGFS_GEM_STATE_EXPORTED_BIT] = "exported",
+ [PANTHOR_DEBUGFS_GEM_STATE_EVICTED_BIT] = "evicted",
};
static const char * const gem_usage_flags_names[] = {
@@ -1625,6 +1630,7 @@ static void panthor_gem_debugfs_bo_print(struct panthor_gem_object *bo,
{
enum panthor_gem_reclaim_state reclaim_state = bo->reclaim_state;
unsigned int refcount = kref_read(&bo->base.refcount);
+ int reclaimed_count = atomic_read(&bo->reclaimed_count);
char creator_info[32] = {};
size_t resident_size;
u32 gem_usage_flags = bo->debugfs.flags;
@@ -1638,16 +1644,20 @@ static void panthor_gem_debugfs_bo_print(struct panthor_gem_object *bo,
snprintf(creator_info, sizeof(creator_info),
"%s/%d", bo->debugfs.creator.process_name, bo->debugfs.creator.tgid);
- seq_printf(m, "%-32s%-16d%-16d%-16zd%-16zd0x%-16lx",
+ seq_printf(m, "%-32s%-16d%-16d%-11d%-16zd%-16zd0x%-16lx",
creator_info,
bo->base.name,
refcount,
+ reclaimed_count,
bo->base.size,
resident_size,
drm_vma_node_start(&bo->base.vma_node));
if (drm_gem_is_imported(&bo->base))
gem_state_flags |= PANTHOR_DEBUGFS_GEM_STATE_FLAG_IMPORTED;
+ else if (!resident_size && reclaimed_count)
+ gem_state_flags |= PANTHOR_DEBUGFS_GEM_STATE_FLAG_EVICTED;
+
if (bo->base.dma_buf)
gem_state_flags |= PANTHOR_DEBUGFS_GEM_STATE_FLAG_EXPORTED;
@@ -1671,8 +1681,8 @@ static void panthor_gem_debugfs_print_bos(struct panthor_device *ptdev,
panthor_gem_debugfs_print_flag_names(m);
- seq_puts(m, "created-by global-name refcount size resident-size file-offset state usage label\n");
- seq_puts(m, "----------------------------------------------------------------------------------------------------------------------------------------------\n");
+ seq_puts(m, "created-by global-name refcount evictions size resident-size file-offset state usage label\n");
+ seq_puts(m, "---------------------------------------------------------------------------------------------------------------------------------------------------------\n");
scoped_guard(mutex, &ptdev->gems.lock) {
list_for_each_entry(bo, &ptdev->gems.node, debugfs.node) {
@@ -1680,7 +1690,7 @@ static void panthor_gem_debugfs_print_bos(struct panthor_device *ptdev,
}
}
- seq_puts(m, "==============================================================================================================================================\n");
+ seq_puts(m, "=========================================================================================================================================================\n");
seq_printf(m, "Total size: %zd, Total resident: %zd, Total reclaimable: %zd\n",
totals.size, totals.resident, totals.reclaimable);
}
diff --git a/drivers/gpu/drm/panthor/panthor_gem.h b/drivers/gpu/drm/panthor/panthor_gem.h
index ae0491d0b121..56d63137b4eb 100644
--- a/drivers/gpu/drm/panthor/panthor_gem.h
+++ b/drivers/gpu/drm/panthor/panthor_gem.h
@@ -19,12 +19,16 @@ struct panthor_vm;
enum panthor_debugfs_gem_state_flags {
PANTHOR_DEBUGFS_GEM_STATE_IMPORTED_BIT = 0,
PANTHOR_DEBUGFS_GEM_STATE_EXPORTED_BIT = 1,
+ PANTHOR_DEBUGFS_GEM_STATE_EVICTED_BIT = 2,
/** @PANTHOR_DEBUGFS_GEM_STATE_FLAG_IMPORTED: GEM BO is PRIME imported. */
PANTHOR_DEBUGFS_GEM_STATE_FLAG_IMPORTED = BIT(PANTHOR_DEBUGFS_GEM_STATE_IMPORTED_BIT),
/** @PANTHOR_DEBUGFS_GEM_STATE_FLAG_EXPORTED: GEM BO is PRIME exported. */
PANTHOR_DEBUGFS_GEM_STATE_FLAG_EXPORTED = BIT(PANTHOR_DEBUGFS_GEM_STATE_EXPORTED_BIT),
+
+ /** @PANTHOR_DEBUGFS_GEM_STATE_FLAG_EVICTED: GEM BO is evicted to swap. */
+ PANTHOR_DEBUGFS_GEM_STATE_FLAG_EVICTED = BIT(PANTHOR_DEBUGFS_GEM_STATE_EVICTED_BIT),
};
enum panthor_debugfs_gem_usage_flags {
@@ -172,6 +176,12 @@ struct panthor_gem_object {
/** @reclaim_state: Cached reclaim state */
enum panthor_gem_reclaim_state reclaim_state;
+ /**
+ * @reclaimed_count: How many times object has been evicted to swap.
+ * The count saturates at %INT_MAX and will never wrap around to 0.
+ */
+ atomic_t reclaimed_count;
+
/**
* @exclusive_vm_root_gem: Root GEM of the exclusive VM this GEM object
* is attached to.
--
2.53.0