Hello Jeff Layton,
To be honest, I'm not sure why I am only seeing this now. These
warnings are hard to analyse because they involve such a long call tree.
Anyway, hopefully it's not too complicated for you since you know the
code.
The patch dee0c5f83460: "libceph: add new iov_iter-based
ceph_msg_data_type and ceph_osd_data_type" from Jul 1, 2022
(linux-next), leads to the following Smatch static checker warning:
lib/iov_iter.c:905 want_pages_array()
warn: sleeping in atomic context
lib/iov_iter.c
896 static int want_pages_array(struct page ***res, size_t size,
897 size_t start, unsigned int maxpages)
898 {
899 unsigned int count = DIV_ROUND_UP(size + start, PAGE_SIZE);
900
901 if (count > maxpages)
902 count = maxpages;
903 WARN_ON(!count); // caller should've prevented that
904 if (!*res) {
--> 905 *res = kvmalloc_array(count, sizeof(struct page *), GFP_KERNEL);
906 if (!*res)
907 return 0;
908 }
909 return count;
910 }
prep_next_sparse_read() <- disables preempt
-> advance_cursor()
-> ceph_msg_data_next()
-> ceph_msg_data_iter_next()
-> iov_iter_get_pages2()
-> __iov_iter_get_pages_alloc()
-> want_pages_array()
The prep_next_sparse_read() functions hold the spin_lock(&o->o_requests_lock);
lock so it can't sleep. But iov_iter_get_pages2() seems like a sleeping
operation.
regards,
dan carpenter
