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 <lijiang@xxxxxxxxxx>
---
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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