The patch titled Subject: ipc/mqueue: switch back to using non-max values on create has been added to the -mm tree. Its filename is ipc-mqueue-switch-back-to-using-non-max-values-on-create.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Doug Ledford <dledford@xxxxxxxxxx> Subject: ipc/mqueue: switch back to using non-max values on create Commit b231cca4381 ("message queues: increase range limits") changed how we create a queue that does not include an attr struct passed to open so that it creates the queue with whatever the maximum values are. However, if the admin has set the maximums to allow flexibility in creating a queue (aka, both a large size and large queue are allowed, but combined they create a queue too large for the RLIMIT_MSGQUEUE of the user), then attempts to create a queue without an attr struct will fail. Switch back to using acceptable defaults regardless of what the maximums are. Note: so far, we only know of a few applications that rely on this behavior (specifically, set the maximums in /proc, then run the application which calls mq_open() without passing in an attr struct, and the application expects the newly created message queue to have the maximum sizes that were set in /proc used on the mq_open() call, and all of those applications that we know of are actually part of regression test suites that were coded to do something like this: for size in 4096 65536 $((1024 * 1024)) $((16 * 1024 * 1024)); do echo $size > /proc/sys/fs/mqueue/msgsize_max mq_open || echo "Error opening mq with size $size" done These test suites that depend on any behavior like this are broken. The concept that programs should rely upon the system wide maximum in order to get their desired results instead of simply using a attr struct to specify what they want is fundamentally unfriendly programming practice for any multi-tasking OS. Fixing this will break those few apps that we know of (and those app authors recognize the brokenness of their code and the need to fix it). However, a future patch will allow a workaround in the form of new knobs for the default msg queue creation parameters for any software out there that we don't already know about that might rely on this behavior at the moment. Signed-off-by: Doug Ledford <dledford@xxxxxxxxxx> Cc: Serge E. Hallyn <serue@xxxxxxxxxx> Cc: Amerigo Wang <amwang@xxxxxxxxxx> Cc: Joe Korty <joe.korty@xxxxxxxx> Cc: Jiri Slaby <jslaby@xxxxxxx> Acked-by: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxxxxxxx> Cc: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/ipc_namespace.h | 2 ++ ipc/mqueue.c | 5 +++-- 2 files changed, 5 insertions(+), 2 deletions(-) diff -puN include/linux/ipc_namespace.h~ipc-mqueue-switch-back-to-using-non-max-values-on-create include/linux/ipc_namespace.h --- a/include/linux/ipc_namespace.h~ipc-mqueue-switch-back-to-using-non-max-values-on-create +++ a/include/linux/ipc_namespace.h @@ -95,9 +95,11 @@ extern int mq_init_ns(struct ipc_namespa #define DFLT_QUEUESMAX 256 /* max number of message queues */ #define HARD_QUEUESMAX 1024 #define MIN_MSGMAX 1 +#define DFLT_MSG 10U #define DFLT_MSGMAX 10 /* max number of messages in each queue */ #define HARD_MSGMAX (32768*sizeof(void *)/4) #define MIN_MSGSIZEMAX 128 +#define DFLT_MSGSIZE 8192U #define DFLT_MSGSIZEMAX 8192 /* max message size */ #define HARD_MSGSIZEMAX (8192*128) #else diff -puN ipc/mqueue.c~ipc-mqueue-switch-back-to-using-non-max-values-on-create ipc/mqueue.c --- a/ipc/mqueue.c~ipc-mqueue-switch-back-to-using-non-max-values-on-create +++ a/ipc/mqueue.c @@ -142,8 +142,9 @@ static struct inode *mqueue_get_inode(st info->qsize = 0; info->user = NULL; /* set when all is ok */ memset(&info->attr, 0, sizeof(info->attr)); - info->attr.mq_maxmsg = ipc_ns->mq_msg_max; - info->attr.mq_msgsize = ipc_ns->mq_msgsize_max; + info->attr.mq_maxmsg = min(ipc_ns->mq_msg_max, DFLT_MSG); + info->attr.mq_msgsize = + min(ipc_ns->mq_msgsize_max, DFLT_MSGSIZE); if (attr) { info->attr.mq_maxmsg = attr->mq_maxmsg; info->attr.mq_msgsize = attr->mq_msgsize; _ Subject: Subject: ipc/mqueue: switch back to using non-max values on create Patches currently in -mm which might be from dledford@xxxxxxxxxx are ipc-mqueue-cleanup-definition-names-and-locations.patch ipc-mqueue-switch-back-to-using-non-max-values-on-create.patch ipc-mqueue-enforce-hard-limits.patch ipc-mqueue-update-maximums-for-the-mqueue-subsystem.patch mqueue-revert-bump-up-dflt_max.patch mqueue-dont-use-kmalloc-with-kmalloc_max_size.patch mqueue-separate-mqueue-default-value-from-maximum-value-v2.patch selftests-add-mq_open_tests.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html