From: Christoph Hellwig <hch@xxxxxx> Subject: kernel: move use_mm/unuse_mm to kthread.c Patch series "improve use_mm / unuse_mm", v2. This series improves the use_mm / unuse_mm interface by better documenting the assumptions, and my taking the set_fs manipulations spread over the callers into the core API. This patch (of 3): Use the proper API instead. Link: http://lkml.kernel.org/r/20200404094101.672954-1-hch@xxxxxx These helpers are only for use with kernel threads, and I will tie them more into the kthread infrastructure going forward. Also move the prototypes to kthread.h - mmu_context.h was a little weird to start with as it otherwise contains very low-level MM bits. Link: http://lkml.kernel.org/r/20200404094101.672954-1-hch@xxxxxx Link: http://lkml.kernel.org/r/20200416053158.586887-1-hch@xxxxxx Link: http://lkml.kernel.org/r/20200404094101.672954-5-hch@xxxxxx Signed-off-by: Christoph Hellwig <hch@xxxxxx> Acked-by: Felix Kuehling <Felix.Kuehling@xxxxxxx> Reviewed-by: Jens Axboe <axboe@xxxxxxxxx> Tested-by: Jens Axboe <axboe@xxxxxxxxx> Cc: Alex Deucher <alexander.deucher@xxxxxxx> Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx> Cc: Felipe Balbi <balbi@xxxxxxxxxx> Cc: Jason Wang <jasowang@xxxxxxxxxx> Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx> Cc: Zhenyu Wang <zhenyuw@xxxxxxxxxxxxxxx> Cc: Zhi Wang <zhi.a.wang@xxxxxxxxx> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h | 1 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_arcturus.c | 1 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v10.c | 1 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v7.c | 2 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v8.c | 2 drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v9.c | 2 drivers/gpu/drm/i915/gvt/kvmgt.c | 2 drivers/usb/gadget/function/f_fs.c | 2 drivers/usb/gadget/legacy/inode.c | 2 drivers/vhost/vhost.c | 1 fs/aio.c | 1 fs/io-wq.c | 1 fs/io_uring.c | 1 include/linux/kthread.h | 5 include/linux/mmu_context.h | 5 kernel/kthread.c | 56 ++++++++ mm/Makefile | 2 mm/mmu_context.c | 64 ---------- 18 files changed, 66 insertions(+), 85 deletions(-) --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_arcturus.c~kernel-move-use_mm-unuse_mm-to-kthreadc +++ a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_arcturus.c @@ -22,7 +22,6 @@ #include <linux/module.h> #include <linux/fdtable.h> #include <linux/uaccess.h> -#include <linux/mmu_context.h> #include <linux/firmware.h> #include "amdgpu.h" #include "amdgpu_amdkfd.h" --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v10.c~kernel-move-use_mm-unuse_mm-to-kthreadc +++ a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v10.c @@ -19,7 +19,6 @@ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR * OTHER DEALINGS IN THE SOFTWARE. */ -#include <linux/mmu_context.h> #include "amdgpu.h" #include "amdgpu_amdkfd.h" #include "gc/gc_10_1_0_offset.h" --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v7.c~kernel-move-use_mm-unuse_mm-to-kthreadc +++ a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v7.c @@ -20,8 +20,6 @@ * OTHER DEALINGS IN THE SOFTWARE. */ -#include <linux/mmu_context.h> - #include "amdgpu.h" #include "amdgpu_amdkfd.h" #include "cikd.h" --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v8.c~kernel-move-use_mm-unuse_mm-to-kthreadc +++ a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v8.c @@ -20,8 +20,6 @@ * OTHER DEALINGS IN THE SOFTWARE. */ -#include <linux/mmu_context.h> - #include "amdgpu.h" #include "amdgpu_amdkfd.h" #include "gfx_v8_0.h" --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v9.c~kernel-move-use_mm-unuse_mm-to-kthreadc +++ a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gfx_v9.c @@ -19,8 +19,6 @@ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR * OTHER DEALINGS IN THE SOFTWARE. */ -#include <linux/mmu_context.h> - #include "amdgpu.h" #include "amdgpu_amdkfd.h" #include "gc/gc_9_0_offset.h" --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h~kernel-move-use_mm-unuse_mm-to-kthreadc +++ a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h @@ -27,6 +27,7 @@ #include <linux/types.h> #include <linux/mm.h> +#include <linux/kthread.h> #include <linux/workqueue.h> #include <kgd_kfd_interface.h> #include <drm/ttm/ttm_execbuf_util.h> --- a/drivers/gpu/drm/i915/gvt/kvmgt.c~kernel-move-use_mm-unuse_mm-to-kthreadc +++ a/drivers/gpu/drm/i915/gvt/kvmgt.c @@ -31,7 +31,7 @@ #include <linux/init.h> #include <linux/device.h> #include <linux/mm.h> -#include <linux/mmu_context.h> +#include <linux/kthread.h> #include <linux/sched/mm.h> #include <linux/types.h> #include <linux/list.h> --- a/drivers/usb/gadget/function/f_fs.c~kernel-move-use_mm-unuse_mm-to-kthreadc +++ a/drivers/usb/gadget/function/f_fs.c @@ -32,7 +32,7 @@ #include <linux/usb/functionfs.h> #include <linux/aio.h> -#include <linux/mmu_context.h> +#include <linux/kthread.h> #include <linux/poll.h> #include <linux/eventfd.h> --- a/drivers/usb/gadget/legacy/inode.c~kernel-move-use_mm-unuse_mm-to-kthreadc +++ a/drivers/usb/gadget/legacy/inode.c @@ -21,7 +21,7 @@ #include <linux/sched.h> #include <linux/slab.h> #include <linux/poll.h> -#include <linux/mmu_context.h> +#include <linux/kthread.h> #include <linux/aio.h> #include <linux/uio.h> #include <linux/refcount.h> --- a/drivers/vhost/vhost.c~kernel-move-use_mm-unuse_mm-to-kthreadc +++ a/drivers/vhost/vhost.c @@ -14,7 +14,6 @@ #include <linux/vhost.h> #include <linux/uio.h> #include <linux/mm.h> -#include <linux/mmu_context.h> #include <linux/miscdevice.h> #include <linux/mutex.h> #include <linux/poll.h> --- a/fs/aio.c~kernel-move-use_mm-unuse_mm-to-kthreadc +++ a/fs/aio.c @@ -27,7 +27,6 @@ #include <linux/file.h> #include <linux/mm.h> #include <linux/mman.h> -#include <linux/mmu_context.h> #include <linux/percpu.h> #include <linux/slab.h> #include <linux/timer.h> --- a/fs/io_uring.c~kernel-move-use_mm-unuse_mm-to-kthreadc +++ a/fs/io_uring.c @@ -55,7 +55,6 @@ #include <linux/fdtable.h> #include <linux/mm.h> #include <linux/mman.h> -#include <linux/mmu_context.h> #include <linux/percpu.h> #include <linux/slab.h> #include <linux/kthread.h> --- a/fs/io-wq.c~kernel-move-use_mm-unuse_mm-to-kthreadc +++ a/fs/io-wq.c @@ -10,7 +10,6 @@ #include <linux/errno.h> #include <linux/sched/signal.h> #include <linux/mm.h> -#include <linux/mmu_context.h> #include <linux/sched/mm.h> #include <linux/percpu.h> #include <linux/slab.h> --- a/include/linux/kthread.h~kernel-move-use_mm-unuse_mm-to-kthreadc +++ a/include/linux/kthread.h @@ -5,6 +5,8 @@ #include <linux/err.h> #include <linux/sched.h> +struct mm_struct; + __printf(4, 5) struct task_struct *kthread_create_on_node(int (*threadfn)(void *data), void *data, @@ -198,6 +200,9 @@ bool kthread_cancel_delayed_work_sync(st void kthread_destroy_worker(struct kthread_worker *worker); +void use_mm(struct mm_struct *mm); +void unuse_mm(struct mm_struct *mm); + struct cgroup_subsys_state; #ifdef CONFIG_BLK_CGROUP --- a/include/linux/mmu_context.h~kernel-move-use_mm-unuse_mm-to-kthreadc +++ a/include/linux/mmu_context.h @@ -4,11 +4,6 @@ #include <asm/mmu_context.h> -struct mm_struct; - -void use_mm(struct mm_struct *mm); -void unuse_mm(struct mm_struct *mm); - /* Architectures that care about IRQ state in switch_mm can override this. */ #ifndef switch_mm_irqs_off # define switch_mm_irqs_off switch_mm --- a/kernel/kthread.c~kernel-move-use_mm-unuse_mm-to-kthreadc +++ a/kernel/kthread.c @@ -1,13 +1,17 @@ // SPDX-License-Identifier: GPL-2.0-only /* Kernel thread helper functions. * Copyright (C) 2004 IBM Corporation, Rusty Russell. + * Copyright (C) 2009 Red Hat, Inc. * * Creation is done via kthreadd, so that we get a clean environment * even if we're invoked from userspace (think modprobe, hotplug cpu, * etc.). */ #include <uapi/linux/sched/types.h> +#include <linux/mm.h> +#include <linux/mmu_context.h> #include <linux/sched.h> +#include <linux/sched/mm.h> #include <linux/sched/task.h> #include <linux/kthread.h> #include <linux/completion.h> @@ -25,6 +29,7 @@ #include <linux/numa.h> #include <trace/events/sched.h> + static DEFINE_SPINLOCK(kthread_create_lock); static LIST_HEAD(kthread_create_list); struct task_struct *kthreadd_task; @@ -1203,6 +1208,57 @@ void kthread_destroy_worker(struct kthre } EXPORT_SYMBOL(kthread_destroy_worker); +/* + * use_mm + * Makes the calling kernel thread take on the specified + * mm context. + * (Note: this routine is intended to be called only + * from a kernel thread context) + */ +void use_mm(struct mm_struct *mm) +{ + struct mm_struct *active_mm; + struct task_struct *tsk = current; + + task_lock(tsk); + active_mm = tsk->active_mm; + if (active_mm != mm) { + mmgrab(mm); + tsk->active_mm = mm; + } + tsk->mm = mm; + switch_mm(active_mm, mm, tsk); + task_unlock(tsk); +#ifdef finish_arch_post_lock_switch + finish_arch_post_lock_switch(); +#endif + + if (active_mm != mm) + mmdrop(active_mm); +} +EXPORT_SYMBOL_GPL(use_mm); + +/* + * unuse_mm + * Reverses the effect of use_mm, i.e. releases the + * specified mm context which was earlier taken on + * by the calling kernel thread + * (Note: this routine is intended to be called only + * from a kernel thread context) + */ +void unuse_mm(struct mm_struct *mm) +{ + struct task_struct *tsk = current; + + task_lock(tsk); + sync_mm_rss(mm); + tsk->mm = NULL; + /* active_mm is still 'mm' */ + enter_lazy_tlb(mm, tsk); + task_unlock(tsk); +} +EXPORT_SYMBOL_GPL(unuse_mm); + #ifdef CONFIG_BLK_CGROUP /** * kthread_associate_blkcg - associate blkcg to current kthread --- a/mm/Makefile~kernel-move-use_mm-unuse_mm-to-kthreadc +++ a/mm/Makefile @@ -41,7 +41,7 @@ obj-y := filemap.o mempool.o oom_kill. maccess.o page-writeback.o \ readahead.o swap.o truncate.o vmscan.o shmem.o \ util.o mmzone.o vmstat.o backing-dev.o \ - mm_init.o mmu_context.o percpu.o slab_common.o \ + mm_init.o percpu.o slab_common.o \ compaction.o vmacache.o \ interval_tree.o list_lru.o workingset.o \ debug.o gup.o $(mmu-y) --- a/mm/mmu_context.c +++ /dev/null @@ -1,64 +0,0 @@ -/* Copyright (C) 2009 Red Hat, Inc. - * - * See ../COPYING for licensing terms. - */ - -#include <linux/mm.h> -#include <linux/sched.h> -#include <linux/sched/mm.h> -#include <linux/sched/task.h> -#include <linux/mmu_context.h> -#include <linux/export.h> - -#include <asm/mmu_context.h> - -/* - * use_mm - * Makes the calling kernel thread take on the specified - * mm context. - * (Note: this routine is intended to be called only - * from a kernel thread context) - */ -void use_mm(struct mm_struct *mm) -{ - struct mm_struct *active_mm; - struct task_struct *tsk = current; - - task_lock(tsk); - active_mm = tsk->active_mm; - if (active_mm != mm) { - mmgrab(mm); - tsk->active_mm = mm; - } - tsk->mm = mm; - switch_mm(active_mm, mm, tsk); - task_unlock(tsk); -#ifdef finish_arch_post_lock_switch - finish_arch_post_lock_switch(); -#endif - - if (active_mm != mm) - mmdrop(active_mm); -} -EXPORT_SYMBOL_GPL(use_mm); - -/* - * unuse_mm - * Reverses the effect of use_mm, i.e. releases the - * specified mm context which was earlier taken on - * by the calling kernel thread - * (Note: this routine is intended to be called only - * from a kernel thread context) - */ -void unuse_mm(struct mm_struct *mm) -{ - struct task_struct *tsk = current; - - task_lock(tsk); - sync_mm_rss(mm); - tsk->mm = NULL; - /* active_mm is still 'mm' */ - enter_lazy_tlb(mm, tsk); - task_unlock(tsk); -} -EXPORT_SYMBOL_GPL(unuse_mm); _
