Commit d69f3bad authored Apr 30, 2013 by Robin Holt Committed by Linus Torvalds May 01, 2013

ipc: sysv shared memory limited to 8TiB



Trying to run an application which was trying to put data into half of
memory using shmget(), we found that having a shmall value below 8EiB-8TiB
would prevent us from using anything more than 8TiB.  By setting
kernel.shmall greater than 8EiB-8TiB would make the job work.

In the newseg() function, ns->shm_tot which, at 8TiB is INT_MAX.

ipc/shm.c:
 458 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 459 {
...
 465         int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
...
 474         if (ns->shm_tot + numpages > ns->shm_ctlall)
 475                 return -ENOSPC;

[akpm@linux-foundation.org: make ipc/shm.c:newseg()'s numpages size_t, not int]
Signed-off-by: Robin Holt <holt@sgi.com>
Reported-by: Alex Thorlton <athorlton@sgi.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 41239fe8

include/linux/ipc_namespace.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -43,8 +43,8 @@ struct ipc_namespace {

		size_t shm_ctlmax;
		size_t shm_ctlall;
		unsigned long shm_tot;
		int shm_ctlmni;
		int shm_tot;
		/*
		* Defines whether IPC_RMID is forced for _all_ shm segments regardless
		* of shmctl()

ipc/shm.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -462,7 +462,7 @@ static int newseg(struct ipc_namespace ns, struct ipc_params params)
		size_t size = params->u.size;
		int error;
		struct shmid_kernel *shp;
		int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
		size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
		struct file * file;
		char name[13];
		int id;

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