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    SubjectRe: 2.6.19-rc2-mm1
    From
    Date
    On Thu, 2006-10-19 at 04:31 +1000, Nick Piggin wrote:
    > Nick Piggin wrote:
    >
    > > I can't see anything yet, but I'll keep looking (and try to reproduce
    > > if I can get TLP working).
    >
    > Ah, it is probably exercising the -EFAULT path, and the code in
    > Andrew's tree goes into an infinite loop I think.
    >
    > We can't test for a fault off the atomic copy, because that needn't
    > indicate an unmapped area. What we need to do is change
    > fault_in_pages_readable to return ret, and catch and return that
    > in the caller if it is an error.
    >
    > My usual workstation is down ATM otherwise I would send you a patch.
    > Unless someone beats me to it, I'll send you one tomorrow.
    >
    > Thanks,
    > Nick
    >

    Here is the test case which reproduces the problem on my ppc box
    consistently. But happens occasionally on amd64 box.

    But writev01 test from LTP always hits the problem on amd64 & ppc64.

    Thanks,
    Badari

    Here is the strace output:

    # strace /tmp/tst
    execve("/tmp/tst", ["/tmp/tst"], [/* 64 vars */]) = 0
    uname({sys="Linux", node="elm3b155", ...}) = 0
    brk(0) = 0x10020000
    open("/etc/ld.so.preload", O_RDONLY) = -1 ENOENT (No such file or
    directory)
    open("/etc/ld.so.cache", O_RDONLY) = 3
    fstat64(3, {st_mode=S_IFREG|0644, st_size=99239, ...}) = 0
    mmap(NULL, 99239, PROT_READ, MAP_PRIVATE, 3, 0) = 0x40030000
    close(3) = 0
    open("/lib/tls/libc.so.6", O_RDONLY) = 3
    read(3, "\177ELF\1\2\1\0\0\0\0\0\0\0\0\0\0\3\0\24\0\0\0\1\0\1\274"...,
    512) = 512
    fstat64(3, {st_mode=S_IFREG|0755, st_size=1401050, ...}) = 0
    mmap(0xfeb0000, 1272876, PROT_READ|PROT_EXEC, MAP_PRIVATE, 3, 0) =
    0xfeb0000
    madvise(0xfeb0000, 1272876, MADV_SEQUENTIAL|0x1) = 0
    mmap(0xffd0000, 131072, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_PRIVATE|
    MAP_FIXED, 3, 0x110000) = 0xffd0000
    close(3) = 0
    munmap(0x40030000, 99239) = 0
    open("writev_data_file", O_RDWR|O_CREAT, 0666) = 3
    writev(3, [{"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0"...,
    64}, {ptrace: umoven: Input/output error
    0xffffffff, 64}, {"\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0
    \0"..., 64}], 3


    Test (shamelessly yanked it from writev01 test):
    =================================================


    #include <stdio.h>
    #include <sys/types.h>
    #include <signal.h>
    #include <sys/uio.h>
    #include <sys/fcntl.h>
    #include <memory.h>
    #include <errno.h>
    #include <sys/mman.h>

    #define K_1 1024

    #define CHUNK 64 /* single chunk */
    #define MAX_IOVEC 16
    #define DATA_FILE "writev_data_file"

    char buf1[K_1], buf2[K_1], buf3[K_1];

    struct iovec wr_iovec[MAX_IOVEC] = {
    {buf1, CHUNK},
    {(caddr_t)-1, CHUNK},
    {(buf1 + CHUNK), CHUNK},
    };


    int main()
    {
    int fd, ret;

    if ((fd = open(DATA_FILE, O_RDWR|O_CREAT, 0666)) < 0) {
    perror("open failed");
    exit(1);
    }

    ret = writev(fd, wr_iovec, 3);
    if (ret < 0) {
    perror("writev failed");
    exit(2);
    }

    close(fd);
    }



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