[PATCH v2 1/5] um: set DONTDUMP and DONTFORK flags on KASAN shadow memory

[Benjamin Berg]

From: Benjamin Berg <benjamin.b...@intel.com>

There is no point in either dumping the KASAN shadow memory or doing
copy-on-write after a fork on these memory regions.

This considerably speeds up coredump generation.

Signed-off-by: Benjamin Berg <benjamin.b...@intel.com>
---
 arch/um/os-Linux/mem.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/arch/um/os-Linux/mem.c b/arch/um/os-Linux/mem.c
index 857e3deab293..72f302f4d197 100644
--- a/arch/um/os-Linux/mem.c
+++ b/arch/um/os-Linux/mem.c
@@ -39,6 +39,18 @@ void kasan_map_memory(void *start, size_t len)
                        strerror(errno));
                exit(1);
        }
+
+       if (madvise(start, len, MADV_DONTDUMP)) {
+               os_info("Couldn't set MAD_DONTDUMP on shadow memory: %s\n.",
+                       strerror(errno));
+               exit(1);
+       }
+
+       if (madvise(start, len, MADV_DONTFORK)) {
+               os_info("Couldn't set MADV_DONTFORK on shadow memory: %s\n.",
+                       strerror(errno));
+               exit(1);
+       }
 }
 
 /* Set by make_tempfile() during early boot. */
-- 
2.47.0