Commit 85462323 authored Jun 08, 2008 by Oleg Nesterov Committed by Ingo Molnar Oct 14, 2008

do_generic_file_read: s/EINTR/EIO/ if lock_page_killable() fails



If lock_page_killable() fails because the task was killed by SIGKILL or
any other fatal signal, do_generic_file_read() returns -EIO.

This seems to be OK, because in fact the userspace won't see this error,
the task will dequeue SIGKILL and exit.

However, /sbin/init is different, it will dequeue SIGKILL, ignore it, and
return to the user-space with the bogus -EIO.

Change the code to return the error code from lock_page_killable(), -EINTR.
This doesn't fix the bug, but perhaps makes sense anyway. Imho, with this
change the code looks a bit more logical, and the "good" init should handle
the spurious EINTR or short read.

Afaics we can also change lock_page_killable() to return -ERESTARTNOINTR,
but this can't prevent the short reads.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

parent 7591103c

mm/filemap.c

+8 −7

Original line number	Diff line number	Diff line
		@@ -1100,8 +1100,9 @@ page_ok:

		page_not_up_to_date:
		/* Get exclusive access to the page ... */
		if (lock_page_killable(page))
		goto readpage_eio;
		error = lock_page_killable(page);
		if (unlikely(error))
		goto readpage_error;

		page_not_up_to_date_locked:
		/* Did it get truncated before we got the lock? */
		@@ -1130,8 +1131,9 @@ readpage:
		}

		if (!PageUptodate(page)) {
		if (lock_page_killable(page))
		goto readpage_eio;
		error = lock_page_killable(page);
		if (unlikely(error))
		goto readpage_error;
		if (!PageUptodate(page)) {
		if (page->mapping == NULL) {
		/*
		@@ -1143,15 +1145,14 @@ readpage:
		}
		unlock_page(page);
		shrink_readahead_size_eio(filp, ra);
		goto readpage_eio;
		error = -EIO;
		goto readpage_error;
		}
		unlock_page(page);
		}

		goto page_ok;

		readpage_eio:
		error = -EIO;
		readpage_error:
		/* UHHUH! A synchronous read error occurred. Report it */
		desc->error = error;

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