Stop playing silly games with the VM_ACCOUNT flag
The mmap_region() code would temporarily set the VM_ACCOUNT flag for
anonymous shared mappings just to inform shmem_zero_setup() that it
should enable accounting for the resulting shm object. It would then
clear the flag after calling ->mmap (for the /dev/zero case) or doing
shmem_zero_setup() (for the MAP_ANON case).
This just resulted in vma merge issues, but also made for just
unnecessary confusion. Use the already-existing VM_NORESERVE flag for
this instead, and let shmem_{zero|file}_setup() just figure it out from
that.
This also happens to make it obvious that the new DRI2 GEM layer uses a
non-reserving backing store for its object allocation - which is quite
possibly not intentional. But since I didn't want to change semantics
in this patch, I left it alone, and just updated the caller to use the
new flag semantics.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/ipc/shm.c b/ipc/shm.c
index a9e09ad..c0a021f 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -368,14 +368,14 @@
file = hugetlb_file_setup(name, size);
shp->mlock_user = current_user();
} else {
- int acctflag = VM_ACCOUNT;
+ int acctflag = 0;
/*
* Do not allow no accounting for OVERCOMMIT_NEVER, even
* if it's asked for.
*/
if ((shmflg & SHM_NORESERVE) &&
sysctl_overcommit_memory != OVERCOMMIT_NEVER)
- acctflag = 0;
+ acctflag = VM_NORESERVE;
file = shmem_file_setup(name, size, acctflag);
}
error = PTR_ERR(file);