Hi All,
In Oreilly book "Understanding Linux kernel", following text written under
section "15.1.3.1. Finding a page":
"The lock_page( ) function, in turn, blocks the current process if the page
is already locked. To that end, it invokes the _ _wait_on_bit_lock( )
function on the PG_locked bit. The latter function puts the current process
in the TASK_UNINTERRUPTIBLE state, stores the process descriptor in a wait
queue, executes the sync_page method of the address_space object to unplug
the request queue of the block device containing the file, and finally
invokes schedule( ) to suspend the process until the PG_locked flag of the
page is cleared. "
The corresponding code in 2.6.16 kernel version:
void fastcall __lock_page(struct page *page)
{
DEFINE_WAIT_BIT(wait, &page->flags, PG_locked);
__wait_on_bit_lock(page_waitqueue(page), &wait, sync_page,
TASK_UNINTERRUPTIBLE);
}
I think "stores the process descriptor in a wait queue" should be corrected
as "stores the page descriptor in a wait queue"
Rgds,
Adil
