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Groups > linux.kernel > #1211935
| From | Jiri Slaby <jslaby@suse.cz> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 3.12 54/82] ipc: modify message queue accounting to not take kernel data structures into account |
| Date | 2015-08-24 11:20 +0200 |
| Message-ID | <q0W54-3om-3@gated-at.bofh.it> (permalink) |
| References | <q0VVn-3cH-1@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
From: Marcus Gelderie <redmnic@gmail.com>
3.12-stable review patch. If anyone has any objections, please let me know.
===============
commit de54b9ac253787c366bbfb28d901a31954eb3511 upstream.
A while back, the message queue implementation in the kernel was
improved to use btrees to speed up retrieval of messages, in commit
d6629859b36d ("ipc/mqueue: improve performance of send/recv").
That patch introducing the improved kernel handling of message queues
(using btrees) has, as a by-product, changed the meaning of the QSIZE
field in the pseudo-file created for the queue. Before, this field
reflected the size of the user-data in the queue. Since, it also takes
kernel data structures into account. For example, if 13 bytes of user
data are in the queue, on my machine the file reports a size of 61
bytes.
There was some discussion on this topic before (for example
https://lkml.org/lkml/2014/10/1/115). Commenting on a th lkml, Michael
Kerrisk gave the following background
(https://lkml.org/lkml/2015/6/16/74):
The pseudofiles in the mqueue filesystem (usually mounted at
/dev/mqueue) expose fields with metadata describing a message
queue. One of these fields, QSIZE, as originally implemented,
showed the total number of bytes of user data in all messages in
the message queue, and this feature was documented from the
beginning in the mq_overview(7) page. In 3.5, some other (useful)
work happened to break the user-space API in a couple of places,
including the value exposed via QSIZE, which now includes a measure
of kernel overhead bytes for the queue, a figure that renders QSIZE
useless for its original purpose, since there's no way to deduce
the number of overhead bytes consumed by the implementation.
(The other user-space breakage was subsequently fixed.)
This patch removes the accounting of kernel data structures in the
queue. Reporting the size of these data-structures in the QSIZE field
was a breaking change (see Michael's comment above). Without the QSIZE
field reporting the total size of user-data in the queue, there is no
way to deduce this number.
It should be noted that the resource limit RLIMIT_MSGQUEUE is counted
against the worst-case size of the queue (in both the old and the new
implementation). Therefore, the kernel overhead accounting in QSIZE is
not necessary to help the user understand the limitations RLIMIT imposes
on the processes.
Signed-off-by: Marcus Gelderie <redmnic@gmail.com>
Acked-by: Doug Ledford <dledford@redhat.com>
Acked-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Davidlohr Bueso <dbueso@suse.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: John Duffy <jb_duffy@btinternet.com>
Cc: Arto Bendiken <arto@bendiken.net>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
ipc/mqueue.c | 5 -----
1 file changed, 5 deletions(-)
diff --git a/ipc/mqueue.c b/ipc/mqueue.c
index bb0248fc5187..82bb5e81ef57 100644
--- a/ipc/mqueue.c
+++ b/ipc/mqueue.c
@@ -143,7 +143,6 @@ static int msg_insert(struct msg_msg *msg, struct mqueue_inode_info *info)
if (!leaf)
return -ENOMEM;
INIT_LIST_HEAD(&leaf->msg_list);
- info->qsize += sizeof(*leaf);
}
leaf->priority = msg->m_type;
rb_link_node(&leaf->rb_node, parent, p);
@@ -188,7 +187,6 @@ try_again:
"lazy leaf delete!\n");
rb_erase(&leaf->rb_node, &info->msg_tree);
if (info->node_cache) {
- info->qsize -= sizeof(*leaf);
kfree(leaf);
} else {
info->node_cache = leaf;
@@ -201,7 +199,6 @@ try_again:
if (list_empty(&leaf->msg_list)) {
rb_erase(&leaf->rb_node, &info->msg_tree);
if (info->node_cache) {
- info->qsize -= sizeof(*leaf);
kfree(leaf);
} else {
info->node_cache = leaf;
@@ -1026,7 +1023,6 @@ SYSCALL_DEFINE5(mq_timedsend, mqd_t, mqdes, const char __user *, u_msg_ptr,
/* Save our speculative allocation into the cache */
INIT_LIST_HEAD(&new_leaf->msg_list);
info->node_cache = new_leaf;
- info->qsize += sizeof(*new_leaf);
new_leaf = NULL;
} else {
kfree(new_leaf);
@@ -1133,7 +1129,6 @@ SYSCALL_DEFINE5(mq_timedreceive, mqd_t, mqdes, char __user *, u_msg_ptr,
/* Save our speculative allocation into the cache */
INIT_LIST_HEAD(&new_leaf->msg_list);
info->node_cache = new_leaf;
- info->qsize += sizeof(*new_leaf);
} else {
kfree(new_leaf);
}
--
2.5.0
--
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[PATCH 3.12 01/82] efi: fix 32bit kernel boot failed problem using efi Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:10 +0200
[PATCH 3.12 67/82] signalfd: fix information leak in signalfd_copyinfo Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 54/82] ipc: modify message queue accounting to not take kernel data structures into account Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 75/82] mm/hwpoison: fix page refcount of unknown non LRU page Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 64/82] x86/ldt: Correct LDT access in single stepping logic Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 44/82] ipmi: fix timeout calculation when bmc is disconnected Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 07/82] ARC: make sure instruction_pointer() returns unsigned value Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 59/82] x86/nmi/64: Switch stacks on userspace NMI entry Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 62/82] rcu: Move lockless_dereference() out of rcupdate.h Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 55/82] ocfs2: fix BUG in ocfs2_downconvert_thread_do_work() Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 60/82] arch: Introduce smp_load_acquire(), smp_store_release() Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 57/82] x86/nmi: Enable nested do_nmi() handling for 64-bit kernels Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 71/82] md/bitmap: return an error when bitmap superblock is corrupt. Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 76/82] xen-blkfront: don't add indirect pages to list when !feature_persistent Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 45/82] sparc64: Fix userspace FPU register corruptions. Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 74/82] ipc,sem: fix use after free on IPC_RMID after a task using same semaphore set exits Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 05/82] freeing unlinked file indefinitely delayed Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 66/82] x86/ldt: Further fix FPU emulation Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 69/82] signal: fix information leak in copy_siginfo_from_user32 Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 80/82] EDAC, ppc4xx: Access mci->csrows array elements properly Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 56/82] md/raid1: extend spinlock to protect raid1_end_read_request against inconsistencies Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 77/82] perf: Fix fasync handling on inherited events Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 63/82] x86/ldt: Make modify_ldt synchronous Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 82/82] rbd: fix copyup completion race Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 78/82] dm thin metadata: delete btrees when releasing metadata snapshot Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 73/82] ipc/sem.c: update/correct memory barriers Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 65/82] x86/ldt: Correct FPU emulation access to LDT Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 68/82] signal: fix information leak in copy_siginfo_to_user Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 81/82] drm/radeon: add new OLAND pci id Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 58/82] x86/nmi/64: Remove asm code that saves CR2 Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 79/82] localmodconfig: Use Kbuild files too Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 61/82] rcu: Provide counterpart to rcu_dereference() for non-RCU situations Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 72/82] mm, vmscan: Do not wait for page writeback for GFP_NOFS allocations Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 46/82] md: use kzalloc() when bitmap is disabled Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 70/82] path_openat(): fix double fput() Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:20 +0200
[PATCH 3.12 39/82] ipr: Fix invalid array indexing for HRRQ Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 38/82] ipr: Fix incorrect trace indexing Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 51/82] ARM: OMAP2+: hwmod: Fix _wait_target_ready() for hwmods without sysc Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 32/82] ARM: realview: fix sparsemem build Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 31/82] hwrng: via-rng - Mark device ID table as __maybe_unused Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 10/82] ALSA: usb-audio: add dB range mapping for some devices Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 33/82] MIPS: Fix sched_getaffinity with MT FPAFF enabled Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 43/82] ima: extend "mask" policy matching support Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 41/82] USB: sierra: add 1199:68AB device ID Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 30/82] 3w-xxxx: fix mis-aligned struct accesses Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 40/82] xhci: fix off by one error in TRB DMA address boundary check Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 53/82] ALSA: hda - fix cs4210_spdif_automute() Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 08/82] genirq: Prevent resend to interrupts marked IRQ_NESTED_THREAD Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 52/82] iscsi-target: Fix iscsit_start_kthreads failure OOPs Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 27/82] vhost: actually track log eventfd file Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 35/82] fsnotify: fix oops in fsnotify_clear_marks_by_group_flags() Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 37/82] ipr: Fix locking for unit attention handling Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 36/82] drm/radeon/combios: add some validation of lvds values Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 47/82] ASoC: pcm1681: Fix setting de-emphasis sampling rate selection Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 50/82] crypto: ixp4xx - Remove bogus BUG_ON on scattered dst buffer Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 29/82] iscsi-target: Fix iser explicit logout TX kthread leak Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 48/82] x86/xen: Probe target addresses in set_aliased_prot() before the hypercall Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 49/82] xen/gntdevt: Fix race condition in gntdev_release() Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
Re: [PATCH 3.12 49/82] xen/gntdevt: Fix race condition in gntdev_release() Luis Henriques <luis.henriques@canonical.com> - 2015-08-25 13:40 +0200
Re: [PATCH 3.12 49/82] xen/gntdevt: Fix race condition in gntdev_release() Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com> - 2015-08-25 14:00 +0200
Re: [PATCH 3.12 49/82] xen/gntdevt: Fix race condition in gntdev_release() Jiri Slaby <jslaby@suse.cz> - 2015-08-25 15:20 +0200
Re: [PATCH 3.12 49/82] xen/gntdevt: Fix race condition in gntdev_release() Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com> - 2015-08-25 16:10 +0200
Re: [PATCH 3.12 49/82] xen/gntdevt: Fix race condition in gntdev_release() Jiri Slaby <jslaby@suse.cz> - 2015-08-27 10:10 +0200
[PATCH 3.12 42/82] ima: add support for new "euid" policy condition Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 34/82] MIPS: Make set_pte() SMP safe. Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:30 +0200
[PATCH 3.12 02/82] futex: Fix a race condition between REQUEUE_PI and task death Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 28/82] iscsi-target: Fix use-after-free during TPG session shutdown Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 09/82] ALSA: usb-audio: Add MIDI support for Steinberg MI2/MI4 Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 15/82] mmc: sdhci-pxav3: fix platform_data is not initialized Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 19/82] blkcg: fix gendisk reference leak in blkg_conf_prep() Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 26/82] rds: rds_ib_device.refcount overflow Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 23/82] xhci: report U3 when link is in resume state Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 03/82] HID: usbhid: add Chicony/Pixart usb optical mouse that needs QUIRK_ALWAYS_POLL Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 18/82] Input: usbtouchscreen - avoid unresponsive TSC-30 touch screen Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 25/82] xhci: do not report PLC when link is in internal resume state Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 22/82] xhci: Calculate old endpoints correctly on device reset Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 24/82] xhci: prevent bus_suspend if SS port resuming in phase 1 Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 06/82] s390/sclp: clear upper register halves in _sclp_print_early Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 17/82] tile: use free_bootmem_late() for initrd Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 04/82] mm: avoid setting up anonymous pages into file mapping Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 16/82] md/raid1: fix test for 'was read error from last working device'. Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 20/82] ata: pmp: add quirk for Marvell 4140 SATA PMP Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 11/82] ALSA: hda - Fix MacBook Pro 5,2 quirk Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 13/82] mac80211: clear subdir_stations when removing debugfs Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 21/82] usb-storage: ignore ZTE MF 823 card reader in mode 0x1225 Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 14/82] mmc: sdhci-esdhc: Make 8BIT bus work Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
[PATCH 3.12 12/82] st: null pointer dereference panic caused by use after kref_put by st_open Jiri Slaby <jslaby@suse.cz> - 2015-08-24 11:40 +0200
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