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.

Reviewed-by: Steven Price <[email protected]>
Signed-off-by: Nicolas Frattaroli <[email protected]>
---
 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 13295d7a593d..068aa935c8fc 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.

-- 
2.54.0

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