'\" t
.\"     Title: unlock_page
.\"    Author: [FIXME: author] [see http://docbook.sf.net/el/author]
.\" Generator: DocBook XSL Stylesheets v1.79.1 <http://docbook.sf.net/>
.\"      Date: June 2017
.\"    Manual: Memory Management in Linux
.\"    Source: Kernel Hackers Manual 4.11.3
.\"  Language: English
.\"
.TH "UNLOCK_PAGE" "9" "June 2017" "Kernel Hackers Manual 4\&.11\&" "Memory Management in Linux"
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.SH "NAME"
unlock_page \- unlock a locked page
.SH "SYNOPSIS"
.HP \w'void\ unlock_page('u
.BI "void unlock_page(struct\ page\ *\ " "page" ");"
.SH "ARGUMENTS"
.PP
\fIstruct page * page\fR
.RS 4
the page
.RE
.SH "DESCRIPTION"
.PP
Unlocks the page and wakes up sleepers in
\fB___wait_on_page_locked\fR\&. Also wakes sleepers in
\fBwait_on_page_writeback\fR
because the wakeup mechanism between PageLocked pages and PageWriteback pages is shared\&. But that\*(Aqs OK \- sleepers in
\fBwait_on_page_writeback\fR
just go back to sleep\&.
.PP
Note that this depends on PG_waiters being the sign bit in the byte that contains PG_locked \- thus the
\fBBUILD_BUG_ON\fR\&. That allows us to clear the PG_locked bit and test PG_waiters at the same time fairly portably (architectures that do LL/SC can test any bit, while x86 can test the sign bit)\&.
.SH "COPYRIGHT"
.br