For system call readahead(), need always return 0 instead of bytes read when succeed. The related commit "fee53ce mm/readahead.c: return the value which force_page_cache_readahead() returns" causes this issue. This bug is found by LTP readahead02 test, the related output: [root@gchenlinux readahead]# ./readahead02 readahead02 0 TINFO : creating test file of size: 67108864 readahead02 0 TINFO : read_testfile(0) readahead02 0 TINFO : read_testfile(1) readahead02 1 TFAIL : unexpected failure - returned value = 16384, expected: 0 readahead02 2 TPASS : offset is still at 0 as expected readahead02 0 TINFO : read_testfile(0) took: 2292819 usec readahead02 0 TINFO : read_testfile(1) took: 3524116 usec readahead02 0 TINFO : read_testfile(0) read: 67108864 bytes readahead02 0 TINFO : read_testfile(1) read: 0 bytes readahead02 3 TPASS : readahead saved some I/O readahead02 0 TINFO : cache can hold at least: 624316 kB readahead02 0 TINFO : read_testfile(0) used cache: 65476 kB readahead02 0 TINFO : read_testfile(1) used cache: 65632 kB readahead02 4 TPASS : using cache as expected After this fix, it can pass LTP common test by readahead01 and readahead02. [root@gchenlinux readahead]# ./readahead01 readahead01 0 TINFO : test_bad_fd -1 readahead01 1 TPASS : expected ret success - returned value = -1 readahead01 2 TPASS : expected failure: TEST_ERRNO=EBADF(9): Bad file descriptor readahead01 0 TINFO : test_bad_fd O_WRONLY readahead01 3 TPASS : expected ret success - returned value = -1 readahead01 4 TPASS : expected failure: TEST_ERRNO=EBADF(9): Bad file descriptor readahead01 0 TINFO : test_invalid_fd pipe readahead01 5 TPASS : expected ret success - returned value = -1 readahead01 6 TPASS : expected failure: TEST_ERRNO=EINVAL(22): Invalid argument readahead01 0 TINFO : test_invalid_fd socket readahead01 7 TPASS : expected ret success - returned value = -1 readahead01 8 TPASS : expected failure: TEST_ERRNO=EINVAL(22): Invalid argument [root@gchenlinux readahead]# ./readahead02 readahead02 0 TINFO : creating test file of size: 67108864 readahead02 0 TINFO : read_testfile(0) readahead02 0 TINFO : read_testfile(1) readahead02 1 TPASS : expected ret success - returned value = 0 readahead02 2 TPASS : offset is still at 0 as expected readahead02 0 TINFO : read_testfile(0) took: 3327468 usec readahead02 0 TINFO : read_testfile(1) took: 2802184 usec readahead02 0 TINFO : read_testfile(0) read: 67108864 bytes readahead02 0 TINFO : read_testfile(1) read: 0 bytes readahead02 3 TPASS : readahead saved some I/O readahead02 0 TINFO : cache can hold at least: 794800 kB readahead02 0 TINFO : read_testfile(0) used cache: 66704 kB readahead02 0 TINFO : read_testfile(1) used cache: 65528 kB readahead02 4 TPASS : using cache as expected Signed-off-by: Chen Gang <gang.chen@xxxxxxxxxxx> --- mm/readahead.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) diff --git a/mm/readahead.c b/mm/readahead.c index 1eee42b..83a202e 100644 --- a/mm/readahead.c +++ b/mm/readahead.c @@ -592,5 +592,5 @@ SYSCALL_DEFINE3(readahead, int, fd, loff_t, offset, size_t, count) } fdput(f); } - return ret; + return ret < 0 ? ret : 0; } -- 1.7.7.6 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>