tree 3c79aaf1df2abc9ccdb6e9231cda607211d523fc
parent c725bfce7968009756ed2836a8cd7ba4dc163011
author Jan Kara <jack@suse.cz> 1448280591 +0100
committer Al Viro <viro@zeniv.linux.org.uk> 1448331330 -0500

vfs: Avoid softlockups with sendfile(2)

The following test program from Dmitry can cause softlockups or RCU
stalls as it copies 1GB from tmpfs into eventfd and we don't have any
scheduling point at that path in sendfile(2) implementation:

        int r1 = eventfd(0, 0);
        int r2 = memfd_create("", 0);
        unsigned long n = 1<<30;
        fallocate(r2, 0, 0, n);
        sendfile(r1, r2, 0, n);

Add cond_resched() into __splice_from_pipe() to fix the problem.

CC: Dmitry Vyukov <dvyukov@google.com>
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>