For deployments of systems with very tight memory and a system resource manager process that can make well-founded decisions on trade-offs, a way to tell panthor that all of a process' swapped-out GPU memory should be swapped back in without touching every page manually is of interest.
Make it possible to do this by adding a new sysfs file, called "mem_claim". Writing a TGID to it will cause panthor to search through all panthor_files associated with that process, and bring all its buffers back from swap. Doing this requires the writer to have the CAP_SYS_RESOURCE capability, even when operating on themselves. Signed-off-by: Nicolas Frattaroli <[email protected]> --- Documentation/ABI/testing/sysfs-driver-panthor-mem | 17 ++++++++++++++ drivers/gpu/drm/panthor/panthor_drv.c | 26 ++++++++++++++++++++++ drivers/gpu/drm/panthor/panthor_mmu.c | 25 +++++++++++++++++++++ drivers/gpu/drm/panthor/panthor_mmu.h | 1 + 4 files changed, 69 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-driver-panthor-mem b/Documentation/ABI/testing/sysfs-driver-panthor-mem index 6639394abed2..41e2c18f641d 100644 --- a/Documentation/ABI/testing/sysfs-driver-panthor-mem +++ b/Documentation/ABI/testing/sysfs-driver-panthor-mem @@ -15,3 +15,20 @@ Description: * -EPERM: insufficient permissions to run a reclaim on given TGID * -EINTR: interrupted by signal * -ESRCH: given TGID is not using panthor, and might not exist at all + +What: /sys/bus/platform/drivers/panthor/.../mem_claim +Date: May 2026 +Contact: Nicolas Frattaroli <[email protected]> +Description: + (WO) Writing to this file will cause GPU memory for all panthor GPU + contexts associated with the TGID that's written to it to be brought + back from swap. The write completes when the operation has finished. + + The writing process requires the CAP_SYS_RESOURCE capability. + + Possible error codes: + * -ERANGE: given TGID is too large/small for the TGID type. + * -EINVAL: given TGID could not be parsed. + * -EPERM: insufficient permissions + * -EINTR: interrupted by signal + * -ESRCH: given TGID is not using panthor, and might not exist at all diff --git a/drivers/gpu/drm/panthor/panthor_drv.c b/drivers/gpu/drm/panthor/panthor_drv.c index 7d19b8785ea3..fb2172b0439c 100644 --- a/drivers/gpu/drm/panthor/panthor_drv.c +++ b/drivers/gpu/drm/panthor/panthor_drv.c @@ -1924,9 +1924,35 @@ static ssize_t mem_reclaim_store(struct device *dev, static DEVICE_ATTR_WO(mem_reclaim); +static ssize_t mem_claim_store(struct device *dev, struct device_attribute *attr, + const char *buf, size_t len) +{ + struct panthor_device *ptdev = dev_get_drvdata(dev); + pid_t tgid; + int ret; + + ret = kstrtoint(buf, 0, &tgid); + if (ret) + return ret; + + if (!capable(CAP_SYS_RESOURCE)) + return -EPERM; + + ret = panthor_run_on_pfiles_of_tgid(ptdev, tgid, panthor_mmu_force_claim); + if (ret < 0) + return ret; + else if (!ret) + return -ESRCH; + + return len; +} + +static DEVICE_ATTR_WO(mem_claim); + static struct attribute *panthor_attrs[] = { &dev_attr_profiling.attr, &dev_attr_mem_reclaim.attr, + &dev_attr_mem_claim.attr, NULL, }; diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c index e185787f5657..7130ba4a24da 100644 --- a/drivers/gpu/drm/panthor/panthor_mmu.c +++ b/drivers/gpu/drm/panthor/panthor_mmu.c @@ -3232,6 +3232,31 @@ void panthor_mmu_force_reclaim(struct panthor_file *pfile) freed, freed_sz, nr_to_scan, remaining); } +/** + * panthor_mmu_force_claim - Swap in all VMs associated with a file + * @pfile: pointer to the &struct panthor_file whose memory to swap in + * + * Attempt to get all GPU memory of @pfile swapped back in. + */ +void panthor_mmu_force_claim(struct panthor_file *pfile) +{ + struct panthor_vm *vm; + unsigned long i; + int ret; + + xa_for_each(&pfile->vms->xa, i, vm) { + struct dma_resv *resv = drm_gpuvm_resv(&vm->base); + + dma_resv_lock(resv, NULL); + ret = drm_gpuvm_validate(&vm->base, NULL); + if (ret) + drm_dbg(&vm->ptdev->base, "drm_gpuvm_validate failed: %pe\n", + ERR_PTR(ret)); + + dma_resv_unlock(resv); + } +} + /** * panthor_mmu_unplug() - Unplug the MMU logic * @ptdev: Device. diff --git a/drivers/gpu/drm/panthor/panthor_mmu.h b/drivers/gpu/drm/panthor/panthor_mmu.h index 34adca4b4e95..460f83eb22a9 100644 --- a/drivers/gpu/drm/panthor/panthor_mmu.h +++ b/drivers/gpu/drm/panthor/panthor_mmu.h @@ -25,6 +25,7 @@ void panthor_mmu_post_reset(struct panthor_device *ptdev); void panthor_mmu_suspend(struct panthor_device *ptdev); void panthor_mmu_resume(struct panthor_device *ptdev); void panthor_mmu_force_reclaim(struct panthor_file *pfile); +void panthor_mmu_force_claim(struct panthor_file *pfile); int panthor_vm_map_bo_range(struct panthor_vm *vm, struct panthor_gem_object *bo, u64 offset, u64 size, u64 va, u32 flags); -- 2.54.0
