On Thu, Aug 15, 2019 at 11:37:56AM +0800, Lianbo Jiang wrote:
> With some corrupted vmcore files, the vmcore-dmesg.txt file may grow
> forever till the kdump disk becomes full, and also probably causes
> the disk error messages as follow:
> ...
> sd 0:0:0:0: [sda] tag#6 FAILED Result: hostbyte=DID_BAD_TARGET
> driverbyte=DRIVER_OK
> sd 0:0:0:0: [sda] tag#6 CDB: Read(10) 28 00 08 06 4c 98 00 00 08 00
> blk_update_request: I/O error, dev sda, sector 134630552
> sd 0:0:0:0: [sda] tag#7 FAILED Result: hostbyte=DID_BAD_TARGET
> driverbyte=DRIVER_OK
> sd 0:0:0:0: [sda] tag#7 CDB: Read(10) 28 00 08 06 4c 98 00 00 08 00
> blk_update_request: I/O error, dev sda, sector 134630552
> ...
>
> If vmcore-dmesg.txt occupies the whole disk, the vmcore can not be
> saved, this is also a problem.
>
> Lets limit the size of vmcore-dmesg.txt to avoid such problems.
>
> Signed-off-by: Lianbo Jiang <liji...@redhat.com>
Thanks, this looks good to me.
Please repost this patch with an updated version of Patch 1/2.
> ---
> vmcore-dmesg/vmcore-dmesg.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/vmcore-dmesg/vmcore-dmesg.c b/vmcore-dmesg/vmcore-dmesg.c
> index ff0d540c9130..5ada3566972b 100644
> --- a/vmcore-dmesg/vmcore-dmesg.c
> +++ b/vmcore-dmesg/vmcore-dmesg.c
> @@ -1,8 +1,18 @@
> #include <elf_info.h>
>
> +/* stole this macro from kernel printk.c */
> +#define LOG_BUF_LEN_MAX (uint32_t)(1 << 31)
> +
> static void write_to_stdout(char *buf, unsigned int nr)
> {
> ssize_t ret;
> + static uint32_t n_bytes = 0;
> +
> + n_bytes += nr;
> + if (n_bytes > LOG_BUF_LEN_MAX) {
> + fprintf(stderr, "The vmcore-dmesg.txt over 2G in size is not
> supported.\n");
> + exit(55);
> + }
>
> ret = write(STDOUT_FILENO, buf, nr);
> if (ret != nr) {
> --
> 2.17.1
>
>
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