On 23-Apr-20 4:43 PM, Li Feng wrote:
Avoid dump all mapped memory to a core dump file when crash.
Otherwise it will very large and it's hard to analyze with gdb.
In my test, it will dump 128GiB memory to a core dump file when integrated
to spdk with default configuration.
Suggested rewording:
Currently, even though memory is mapped with PROT_NONE, this does not
cause it to be excluded from core dumps. This is counter-productive,
because in a lot of cases, this memory will go unused (e.g. when the
memory subsystem preallocates VA space but hasn't yet mapped physical
pages into it).
Use `madvise()` call with MADV_DONTDUMP parameter to exclude the
unmapped memory from being dumped.
Signed-off-by: Li Feng <fen...@smartx.com>
---
lib/librte_eal/common/eal_common_memory.c | 14 ++++++++++++++
1 file changed, 14 insertions(+)
diff --git a/lib/librte_eal/common/eal_common_memory.c
b/lib/librte_eal/common/eal_common_memory.c
index cc7d54e0c..2d9564b28 100644
--- a/lib/librte_eal/common/eal_common_memory.c
+++ b/lib/librte_eal/common/eal_common_memory.c
@@ -177,6 +177,20 @@ eal_get_virtual_area(void *requested_addr, size_t *size,
after_len = RTE_PTR_DIFF(map_end, aligned_end);
if (after_len > 0)
munmap(aligned_end, after_len);
+
+ /*
+ * Exclude this pages from a core dump.
+ */
+ if (madvise(aligned_addr, *size, MADV_DONTDUMP) != 0)
+ RTE_LOG(WARNING, EAL, "Madvise with MADV_DONTDUMP failed:
%s\n",
+ strerror(errno)); > + } else {
+ /*
+ * Exclude this pages from a core dump.
+ */
+ if (madvise(mapped_addr, map_sz, MADV_DONTDUMP) != 0)
+ RTE_LOG(WARNING, EAL, "Madvise with MADV_DONTDUMP failed:
%s\n",
+ strerror(errno));
}
return aligned_addr;
For the contents of this patch,
Acked-by: Anatoly Burakov <anatoly.bura...@intel.com>
However, even though this is good to have, after some more thought, i
believe the fix is incomplete, because this is not the only place we're
reserving anonymous memory. We're also doing so in
`eal_memalloc.c:free_seg()`, so an `madvise()` call should also be added
there.
@David, now that i think of it, the PROT_NONE patch also was incomplete,
as we only set PROT_NONE to memory that's initially reserved, but not
when it's unmapped and returned back to the pool of anonymous memory.
So, eal_memalloc.c should also remap anonymous memory with PROT_NONE.
@Li Feng, would you be so kind as to provide a patch replacing PROT_READ
with PROT_NONE in eal_memalloc.c as well? Thank you very much!
--
Thanks,
Anatoly
