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Commit bf8f972d authored by Badari Pulavarty's avatar Badari Pulavarty Committed by Linus Torvalds
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[PATCH] SHM_NORESERVE flags for shmget() 



Add SHM_NORESERVE functionality similar to MAP_NORESERVE for shared memory
segments.

This is mainly to avoid abuse of OVERCOMMIT_ALWAYS and this flag is ignored
for OVERCOMMIT_NEVER.

Signed-off-by: default avatarBadari Pulavarty <pbadari@us.ibm.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent d8ba3b73

include/linux/shm.h

+1 −0
Original line number Diff line number Diff line
@@ -92,6 +92,7 @@ struct shmid_kernel /* private to the kernel */ 
#define	SHM_DEST	01000	/* segment will be destroyed on last detach */

#define SHM_LOCKED      02000   /* segment will not be swapped */

#define SHM_HUGETLB     04000   /* segment will use huge TLB pages */

#define SHM_NORESERVE   010000  /* don't check for reservations */



#ifdef CONFIG_SYSVIPC

long do_shmat(int shmid, char __user *shmaddr, int shmflg, unsigned long *addr);

ipc/shm.c

+9 −1
Original line number Diff line number Diff line
@@ -212,8 +212,16 @@ static int newseg (key_t key, int shmflg, size_t size) 
		file = hugetlb_zero_setup(size);

		shp->mlock_user = current->user;

	} else {

		int acctflag = VM_ACCOUNT;

		/*

		 * 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;

		sprintf (name, "SYSV%08x", key);

		file = shmem_file_setup(name, size, VM_ACCOUNT);

		file = shmem_file_setup(name, size, acctflag);

	}

	error = PTR_ERR(file);

	if (IS_ERR(file))