Re: [dpdk-dev] [PATCH v2] eal: add madvise to avoid dump memory

[Feng Li <lifeng1519@gmail.com>]

Bruce Richardson <bruce.richardson@intel.com> 于2020年4月24日周五 下午5:14写道：
>
> On Fri, Apr 24, 2020 at 10:12:10AM +0100, Burakov, Anatoly wrote:
> > On 23-Apr-20 9:04 PM, David Marchand wrote:
> > > On Thu, Apr 23, 2020 at 6:34 PM Burakov, Anatoly
> > > <anatoly.burakov@intel.com> wrote:
> > > > > 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,
> > >
> > > MADV_DONTDUMP does not seem POSIX, but as I said [1], there seems to
> > > be a MADV_NOCORE option on FreeBSD.
> > > 1: http://inbox.dpdk.org/dev/CAJFAV8y9YtT-7njUz+mD6U8+3XUqYrgp28KD7jy2923EpAcXrg@mail.gmail.com/
> > >
> > >
> >
> > Oh, right, so this would probably not compile on FreeBSD. Perhaps this
> > function would have to be OS-specific after all (or call into an OS-specific
> > madvise() after reserving the memory area).
> >
>
> Is it just a differently named flag? If so, I think a single #ifdef macro
> won't kill us in the common code.
>
Just the flag name is different.
I should use RTE_EXEC_ENV_FREEBSD and RTE_EXEC_ENV_LINUX, right?

Another question, in `eal_memalloc.c:alloc_seg`, I should undo the
DONTMAP of the memory region.
Right? @Anatoly

Just few minutes, I have prepared a patch for the OS-specific code:
--- a/lib/librte_eal/common/eal_private.h
+++ b/lib/librte_eal/common/eal_private.h
@@ -443,4 +443,20 @@ rte_option_usage(void);
 uint64_t
 eal_get_baseaddr(void);

+/**
+ * @internal
+ * Exclude this pages from a core dump.
+ *
+ * @param addr
+ *  The memory region starts.
+ *
+ * @param len
+ *  The memory region length..
+ *
+ * @return
+ * returns 0 or -errno
+ */
+int
+eal_madvise_dontdump(void* addr, size_t len);
+
 #endif /* _EAL_PRIVATE_H_ */
diff --git a/lib/librte_eal/freebsd/eal_memory.c
b/lib/librte_eal/freebsd/eal_memory.c
index a97d8f0f0..585042dde 100644
--- a/lib/librte_eal/freebsd/eal_memory.c
+++ b/lib/librte_eal/freebsd/eal_memory.c
@@ -534,3 +534,9 @@ rte_eal_memseg_init(void)
  memseg_primary_init() :
  memseg_secondary_init();
 }
+
+int
+eal_madvise_dontdump(void* addr, size_t len)
+{
+ return madvise(addr, len, MADV_NOCORE);
+}
diff --git a/lib/librte_eal/linux/eal_memory.c
b/lib/librte_eal/linux/eal_memory.c
index 7a9c97ff8..cfdbfccfe 100644
--- a/lib/librte_eal/linux/eal_memory.c
+++ b/lib/librte_eal/linux/eal_memory.c
@@ -2479,3 +2479,9 @@ rte_eal_memseg_init(void)
 #endif
  memseg_secondary_init();
 }
+
+int
+eal_madvise_dontdump(void* addr, size_t len)
+{
+ return madvise(addr, len, MADV_DONTDUMP);
+}