[Crash-utility] [PATCH] Enhance the "kmem -i" option to properly display the statistics of CACHED
The "kmem -i" option may output the bogus statistics of CACHED, which
might be observed when some extreme situations occur in kernel, such as
OOM, disk IO errors, etc.
The following result of calculation may be a negative value, refer to
the dump_kmeminfo():
page_cache_size = nr_file_pages - swapper_space_nrpages - buffer_pages;
As a result, the negative value will be converted to unsigned long
integer, eventually it overflows and gets a big integer.
crash> kmem -i
PAGES TOTAL PERCENTAGE
TOTAL MEM 255314511 973.9 GB ----
FREE 533574 2 GB 0% of TOTAL MEM
USED 254780937 971.9 GB 99% of TOTAL MEM
SHARED 1713 6.7 MB 0% of TOTAL MEM
BUFFERS 374 1.5 MB 0% of TOTAL MEM
CACHED -114 70368744177664 GB 72251060080% of TOTAL MEM
^^^^ ^^^^^^^^^^^^^^ ^^^^^^^^^^^^
...
Let's normalize it to zero to fix such corner cases.
Reported-by: Buland Kumar Singh <bsingh(a)redhat.com>
Signed-off-by: Lianbo Jiang <lijiang(a)redhat.com>
---
memory.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/memory.c b/memory.c
index e0742c1bd3a4..860a3a978a4d 100644
--- a/memory.c
+++ b/memory.c
@@ -8615,6 +8615,8 @@ dump_kmeminfo(void)
page_cache_size = 0;
+ if (page_cache_size < 0)
+ page_cache_size = 0;
pct = (page_cache_size * 100)/totalram_pages;
fprintf(fp, "%13s %7ld %11s %3ld%% of TOTAL MEM\n",
"CACHED", page_cache_size,
--
2.37.1