On 2018/1/25 10:58, Al Viro wrote:
On Thu, Jan 25, 2018 at 10:46:26AM +0800, Jia-Ju Bai wrote:
The function ioc_create_icq here is not called in atomic context.
Thus GFP_ATOMIC is not necessary, and it can be replaced with GFP_KERNEL.
This is found by a static analysis tool named DCNS written by myself.
Umm... Some human-readable analysis would be welcome. FWIW, I've tried to
put a proof together, but...
struct blk_mq_ops->timeout = nvme_timeout
nvme_timeout()
nvme_alloc_request()
blk_mq_alloc_request_hctx()
blk_mq_get_request()
blk_mq_sched_assign_ioc()
... and while I have not traced the call chain further, the look of that
function (nvme_timeout()) strongly suggests that it *is* meant to be
called from bloody atomic context.
"My tool has found that place/put together a proof" is nice, but it
doesn't replace the proof itself...
Thanks for reply :)
I have checked the given call chain, and find that nvme_dev_disable in
nvme_timeout calls mutex_lock that can sleep.
Thus, I suppose this call chain is not in atomic context.
Besides, how do you find that "function (nvme_timeout()) strongly
suggests that it *is* meant to be called from bloody atomic context"?
I check the comments in nvme_timeout, and do not find related description...
By the way, do you mean that I should add "My tool has proved that this
function is never called in atomic context" in the description?
Thanks,
Jia-Ju Bai
