Not able to understand the first code block of follow_page_mask
function. follow_huge_addr function is expected to find the page
struct for the given address if it turns out to be a HugeTLB page
but then when it finds the page we bug on if it had been called
with FOLL_GET flag.
page = follow_huge_addr(mm, address, flags & FOLL_WRITE);
if (!IS_ERR(page)) {
BUG_ON(flags & FOLL_GET);
return page;
}
do_move_page_to_node_array calls follow_page with FOLL_GET which
in turn calls follow_page_mask with FOLL_GET. On POWER, the
function follow_huge_addr is defined and does not return -EINVAL
like the generic one. It returns the page struct if its a HugeTLB
page. Just curious to know what is the purpose behind the BUG_ON.
Thank you.
Regards
Anshuman
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