diff options
| author | Christoph Hellwig | 2020-06-10 18:42:10 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2020-06-10 19:14:18 -0700 |
| commit | 37c54f9bd48663f7657a9178fe08c47e4f5b537b (patch) | |
| tree | ba38e9216da172c16c4beafa97a882fc85f86068 /fs | |
| parent | f5678e7f2ac31c270334b936352f0ef2fe7dd2b3 (diff) | |
kernel: set USER_DS in kthread_use_mm
Some architectures like arm64 and s390 require USER_DS to be set for
kernel threads to access user address space, which is the whole purpose of
kthread_use_mm, but other like x86 don't. That has lead to a huge mess
where some callers are fixed up once they are tested on said
architectures, while others linger around and yet other like io_uring try
to do "clever" optimizations for what usually is just a trivial asignment
to a member in the thread_struct for most architectures.
Make kthread_use_mm set USER_DS, and kthread_unuse_mm restore to the
previous value instead.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: Jens Axboe <axboe@kernel.dk>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Felipe Balbi <balbi@kernel.org>
Cc: Felix Kuehling <Felix.Kuehling@amd.com>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Zhenyu Wang <zhenyuw@linux.intel.com>
Cc: Zhi Wang <zhi.a.wang@intel.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: http://lkml.kernel.org/r/20200404094101.672954-7-hch@lst.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/io-wq.c | 8 | ||||
| -rw-r--r-- | fs/io_uring.c | 4 |
2 files changed, 2 insertions, 10 deletions
diff --git a/fs/io-wq.c b/fs/io-wq.c index 748621f7391e..a5e90ac39e4d 100644 --- a/fs/io-wq.c +++ b/fs/io-wq.c @@ -169,7 +169,6 @@ static bool __io_worker_unuse(struct io_wqe *wqe, struct io_worker *worker) dropped_lock = true; } __set_current_state(TASK_RUNNING); - set_fs(KERNEL_DS); kthread_unuse_mm(worker->mm); mmput(worker->mm); worker->mm = NULL; @@ -421,14 +420,11 @@ static void io_wq_switch_mm(struct io_worker *worker, struct io_wq_work *work) mmput(worker->mm); worker->mm = NULL; } - if (!work->mm) { - set_fs(KERNEL_DS); + if (!work->mm) return; - } + if (mmget_not_zero(work->mm)) { kthread_use_mm(work->mm); - if (!worker->mm) - set_fs(USER_DS); worker->mm = work->mm; /* hang on to this mm */ work->mm = NULL; diff --git a/fs/io_uring.c b/fs/io_uring.c index ec4e9d36210b..26f7bc941d01 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -5989,15 +5989,12 @@ static int io_sq_thread(void *data) { struct io_ring_ctx *ctx = data; const struct cred *old_cred; - mm_segment_t old_fs; DEFINE_WAIT(wait); unsigned long timeout; int ret = 0; complete(&ctx->sq_thread_comp); - old_fs = get_fs(); - set_fs(USER_DS); old_cred = override_creds(ctx->creds); timeout = jiffies + ctx->sq_thread_idle; @@ -6102,7 +6099,6 @@ static int io_sq_thread(void *data) if (current->task_works) task_work_run(); - set_fs(old_fs); io_sq_thread_drop_mm(ctx); revert_creds(old_cred); |