From: William Lee Irwin III <wli@holomorphy.com>
During the kernel summit, some discussion was had about the support
requirements for a userspace program loader that loads executables into
hugetlb on behalf of a major application (Oracle). In order to support
this in a robust fashion, the cleanup of the hugetlb must be robust in the
presence of disorderly termination of the programs (e.g. kill -9). Hence,
the cleanup semantics are those of System V shared memory, but Linux'
System V shared memory needs one critical extension for this use:
executability.
The following microscopic patch enables this major application to provide
robust hugetlb cleanup.
Signed-off-by: Andrew Morton <akpm@osdl.org>
---
25-akpm/include/linux/shm.h | 1 +
25-akpm/ipc/shm.c | 4 ++++
2 files changed, 5 insertions(+)
diff -puN include/linux/shm.h~executable-hugetlb-pages include/linux/shm.h
--- 25/include/linux/shm.h~executable-hugetlb-pages 2004-08-09 02:06:56.445226264 -0700
+++ 25-akpm/include/linux/shm.h 2004-08-09 02:06:56.452225200 -0700
@@ -44,6 +44,7 @@ struct shmid_ds {
#define SHM_RDONLY 010000 /* read-only access */
#define SHM_RND 020000 /* round attach address to SHMLBA boundary */
#define SHM_REMAP 040000 /* take-over region on attach */
+#define SHM_EXEC 0100000 /* execution access */
/* super user shmctl commands */
#define SHM_LOCK 11
diff -puN ipc/shm.c~executable-hugetlb-pages ipc/shm.c
--- 25/ipc/shm.c~executable-hugetlb-pages 2004-08-09 02:06:56.447225960 -0700
+++ 25-akpm/ipc/shm.c 2004-08-09 02:06:56.453225048 -0700
@@ -688,6 +688,10 @@ long do_shmat(int shmid, char __user *sh
o_flags = O_RDWR;
acc_mode = S_IRUGO | S_IWUGO;
}
+ if (shmflg & SHM_EXEC) {
+ prot |= PROT_EXEC;
+ acc_mode |= S_IXUGO;
+ }
/*
* We cannot rely on the fs check since SYSV IPC does have an
_