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I'm looking for a way to keep track of the processes that fail to allocate new
virtual memory. What do you think about the following approach (untested)?
--
Print informations about the processes that fail to allocate virtual memory.
Signed-off-by: Andrea Righi <a.righi@cineca.it>
diff -urpN linux-2.6.21/mm/mmap.c linux-2.6.21-vm-log-enomem/mm/mmap.c
--- linux-2.6.21/mm/mmap.c 2007-04-26 05:08:32.000000000 +0200
+++ linux-2.6.21-vm-log-enomem/mm/mmap.c 2007-05-17 18:05:39.000000000 +0200
@@ -77,6 +77,26 @@ int sysctl_max_map_count __read_mostly =
atomic_t vm_committed_space = ATOMIC_INIT(0);
/*
+ * Print current process informations when it fails to allocate new virtual
+ * memory.
+ */
+static inline void log_vm_enomem(void)
+{
+ unsigned long total_vm = 0;
+ struct mm_struct *mm;
+
+ task_lock(current);
+ mm = current->mm;
+ if (mm)
+ total_vm = mm->total_vm;
+ task_unlock(current);
+
+ printk(KERN_INFO
+ "out of virtual memory for process %d (%s): total_vm=%lu, uid=%d\n",
+ current->pid, current->comm, total_vm, current->uid);
+}
+
+/*
* Check that a process has enough memory to allocate a new virtual
* mapping. 0 means there is enough memory for the allocation to
* succeed and -ENOMEM implies there is not.
@@ -175,6 +195,7 @@ int __vm_enough_memory(long pages, int c
return 0;
error:
vm_unacct_memory(pages);
+ log_vm_enomem();
return -ENOMEM;
}
-
Looks like an easy way for users to spam syslogd over and over and over again. At the very least, shouldn't this be dependant on print_fatal_signals? -- Politics is the struggle between those who want to make their country the best in the world, and those who believe it already is. Each group calls the other unpatriotic. -
Speaking of signals, everytime I get a segfault (or force one with a test program) on x86_64, the kernel prints to dmesg: fail[22278]: segfault at 0000000000000000 rip 00000000004004b8 rsp 00007ffff7ecda50 error 6 I do not see such on i386, so why for x86_64? Jan -- -
So that you know that one of your programs crashed. That's a feature. -Andi -
This feature could be handy for i386 too. Jan -- -
What about your /proc/sys/kernel/print-fatal-signals? it must be set to 1 to enable that feature. -Andrea -
That file does not exist on versions 2.6.18 <= version <= 2.6.20 Jan -- -
This means that you must apply the print_fatal_signals patch... -Andrea -
Since 2.6.18.2 I use this patch. With 2.6.21.1 it still applies altough
with a small offsets. Works like a charm.
Signed-off by: Folkert van Heusden <folkert@vanheusden.com>
--- linux-2.6.18.2/kernel/signal.c 2006-11-04 02:33:58.000000000 +0100
+++ linux-2.6.18.2.new/kernel/signal.c 2006-11-17 15:59:13.000000000 +0100
@@ -706,6 +706,15 @@
struct sigqueue * q = NULL;
int ret = 0;
+ if (sig == SIGQUIT || sig == SIGILL || sig == SIGTRAP ||
+ sig == SIGABRT || sig == SIGBUS || sig == SIGFPE ||
+ sig == SIGSEGV || sig == SIGXCPU || sig == SIGXFSZ ||
+ sig == SIGSYS || sig == SIGSTKFLT)
+ {
+ printk(KERN_WARNING "Sig %d send to %d owned by %d.%d (%s)\n",
+ sig, t -> pid, t -> uid, t -> gid, t -> comm);
+ }
+
/*
* fast-pathed signals for kernel-internal things like SIGSTOP
* or SIGKILL.
Folkert van Heusden
--
www.biglumber.com <- site where one can exchange PGP key signatures
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-
Please check line 219 of Documentation/CodingStyle, Section 3.1: Spaces and no space around the '.' and "->" structure member operators. Thank you -
New version without the spaces around '->' and a nice 'unlikely' added.
Signed-off by: Folkert van Heusden <folkert@vanheusden.com>
--- linux-2.6.18.2/kernel/signal.c 2006-11-04 02:33:58.000000000 +0100
+++ linux-2.6.18.2.new/kernel/signal.c 2006-11-17 15:59:13.000000000 +0100
@@ -706,6 +706,15 @@
struct sigqueue * q = NULL;
int ret = 0;
+ if (unlikely(sig == SIGQUIT || sig == SIGILL || sig == SIGTRAP ||
+ sig == SIGABRT || sig == SIGBUS || sig == SIGFPE ||
+ sig == SIGSEGV || sig == SIGXCPU || sig == SIGXFSZ ||
+ sig == SIGSYS || sig == SIGSTKFLT))
+ {
+ printk(KERN_WARNING "Sig %d send to %d owned by %d.%d (%s)\n",
+ sig, t->pid, t->uid, t->gid, t->comm);
+ }
+
/*
* fast-pathed signals for kernel-internal things like SIGSTOP
* or SIGKILL.
Folkert van Heusden
--
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-
On Sun, 20 May 2007 13:21:11 +0200 Would turning that into a switch() generate better code. -- Stephen Hemminger <shemminger@linux-foundation.org> -
Doubt it: in the worst case you still nee to check for each possibility. Furthermore a.f.a.i.k. with switch you cannot do 'unlinkely()'. Folkert van Heusden -- MultiTail er et flexible tool for å kontrolere Logfiles og commandoer. Med filtrer, farger, sammenføringer, forskeliger ansikter etc. http://www.vanheusden.com/multitail/ ---------------------------------------------------------------------- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com -
With if(), it generates a ton of "CMP, JE" instructions. With switch(), I would assume gcc transforms it into using a jump table (aka "JMP [table+sig]") I tried it: with switch(), gcc transforms this into a bitmap comparison ("MOV eax, 1; SHL eax, sig; TEST eax, 0x830109f8"), which seems even cheaper than a jump table. Jan -- -
Ok, here's the new patch against 2.6.21.1:
Signed-off by Folkert van Heusden <folkert@vanheusden.com>
--- kernel/signal.c.org 2007-05-20 22:47:13.000000000 +0200
+++ kernel/signal.c 2007-05-20 22:54:17.000000000 +0200
@@ -739,6 +739,25 @@
struct sigqueue * q = NULL;
int ret = 0;
+ /* emit some logging for nasty signals
+ * especially SIGSEGV and friends aught to be looked at when happening
+ */
+ switch(sig) {
+ case SIGQUIT:
+ case SIGILL:
+ case SIGTRAP:
+ case SIGABRT:
+ case SIGBUS:
+ case SIGFPE:
+ case SIGSEGV:
+ case SIGXCPU:
+ case SIGXFSZ:
+ case SIGSYS:
+ case SIGSTKFLT:
+ printk(KERN_WARNING "Sig %d send to %d owned by %d.%d (%s)\n",
+ sig, t -> pid, t -> uid, t -> gid, t -> comm);
+ }
+
/*
* fast-pathed signals for kernel-internal things like SIGSTOP
* or SIGKILL.
Folkert van Heusden
--
MultiTail è uno flexible tool per seguire di logfiles e effettuazione
di commissioni. Feltrare, provedere da colore, merge, 'diff-view',
etc. http://www.vanheusden.com/multitail/
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-
Unconditional? That's definitely a very bad idea. If anything only unhandled signals should be printed this way because some programs use them internally. But I think your list is far too long anyways. -Andi -
Use these signals internally? Afaik these are fatal, stopping the So, which ones would you like to have removed then? Folkert van Heusden -- To MultiTail einai ena polymorfiko ergaleio gia ta logfiles kai tin eksodo twn entolwn. Prosferei: filtrarisma, xrwmatismo, sygxwneysi, diaforetikes provoles. http://www.vanheusden.com/multitail/ ---------------------------------------------------------------------- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com -
(and why, of course, to enlighten me: some are educated guesses) Folkert van Heusden -- MultiTail ist eine flexible Applikation um Logfiles und Kommando Eingaben zu überprüfen. Inkl. Filter, Farben, Zusammenführen, Ansichten etc. http://www.vanheusden.com/multitail/ ---------------------------------------------------------------------- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com -
SIGFPE at least and the accounting signals are dubious too. SIGQUIT can be also relatively common. -Andi -
And SIGSEGV and SIGBUS - UML catches these internally and handles them. Jeff -
For example mplayer uses SIGSEGV: it does not check ALL of the possible error situations, in case of SIGSEGV (a bad stream etc) it quickly reinit itself from the last position. It's much better in performance (well sure for a stream without error, or only few of them) than to check all of the possible problems. Nowdays it may not a problem to check everything but it WAS when MPlayer born (much slower CPUs). But some signals are also useful for emulation etc (eg in my own DOS emulator some years ago ....). -- - Gábor -
Maybe you could use somthing similar to unhandled_signal() in arch/x86_64/mm/fault.c, but I agree that the list seems a bit too long... -Andrea -
What about the following enhancement: I check with sig_fatal if it would
kill the process and only then emit a message. So when an application
takes care itself of handling it nothing is printed.
Signed-off by: Folkert van Heusden <folkert@vanheusden.com>
--- kernel/signal.c.org 2007-05-20 22:47:13.000000000 +0200
+++ kernel/signal.c 2007-05-21 12:59:52.000000000 +0200
@@ -739,6 +739,8 @@
struct sigqueue * q = NULL;
int ret = 0;
+ /* emit some logging for unhandled signals
+ */
+ if (sig_fatal(t, sig))
+ {
+ printk(KERN_WARNING "Sig %d send to %d owned by %d.%d (%s)\n",
+ sig, t -> pid, t -> uid, t -> gid, t -> comm);
+ }
+
/*
* fast-pathed signals for kernel-internal things like SIGSTOP
* or SIGKILL.
of course, this can also be limited to only the interesting signals:
Signed-off by: Folkert van Heusden <folkert@vanheusden.com>
--- kernel/signal.c.org 2007-05-20 22:47:13.000000000 +0200
+++ kernel/signal.c 2007-05-21 12:59:52.000000000 +0200
@@ -739,6 +739,28 @@
struct sigqueue * q = NULL;
int ret = 0;
+ /* emit some logging for nasty signals
+ * especially SIGSEGV and friends aught to be looked at when happening
+ */
+ switch(sig) {
+ case SIGQUIT:
+ case SIGILL:
+ case SIGTRAP:
+ case SIGABRT:
+ case SIGBUS:
+ case SIGFPE:
+ case SIGSEGV:
+ case SIGXCPU:
+ case SIGXFSZ:
+ case SIGSYS:
+ case SIGSTKFLT:
+ if (sig_fatal(t, sig))
+ {
+ printk(KERN_WARNING "Sig %d send to %d owned by %d.%d (%s)\n",
+ sig, t -> pid, t -> uid, t -> gid, t -> comm);
+ }
+ }
+
/*
* fast-pathed signals for kernel-internal things like SIGSTOP
* or SIGKILL.
Folkert van Heusden
--
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-
Can we already use that one in send_signal? As the signal needs to be
send first I think before we know if it was handled or not? sig_fatal
checks if the handler is set to default - which is it is not taken care
Description:
This patch adds code to the signal-sender making it log a message when
an unhandled fatal signal will be delivered.
Signed-off by: Folkert van Heusden <folkert@vanheusden.com>
--- kernel/signal.c.org 2007-05-20 22:47:13.000000000 +0200
+++ kernel/signal.c 2007-05-21 14:46:05.000000000 +0200
@@ -739,6 +739,12 @@
struct sigqueue * q = NULL;
int ret = 0;
+ /* unhandled fatal signals are logged */
+ if (sig_fatal(t, sig)) {
+ printk(KERN_WARNING "Sig %d sent to %d owned by %d.%d (%s)\n",
+ sig, t->pid, t->uid, t->gid, t->comm);
+ }
+
/*
* fast-pathed signals for kernel-internal things like SIGSTOP
* or SIGKILL.
Folkert van Heusden
--
MultiTail è uno flexible tool per seguire di logfiles e effettuazione
di commissioni. Feltrare, provedere da colore, merge, 'diff-view',
etc. http://www.vanheusden.com/multitail/
----------------------------------------------------------------------
Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com
-
What about ptrace()'d processes? I don't think we should log signals for them... -Andrea -
Why not? Folkert van Heusden -- MultiTail es una herramienta flexibele para consiguir archivos de log, y para ejecutar ordenes. Filtrar, añadir colores, merger y vista de las differencias. http://www.vanheusden.com/multitail/ ---------------------------------------------------------------------- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com -
Maybe sometimes it's useful, maybe not, but I suppose that usually only the controlling process should care about the critical signals received by the controlled process. I simply don't think it should be a system issue. For example I wouldn't like to have a lot of messages in the kernel logs just because I'm debugging some segfaulting programs with gdb. -Andrea -
Gargh ... why does this want to be in the *kernel*'s logs? In any case, can you please make this KERN_INFO (or lower) instead of KERN_WARNING. -
Description:
This patch adds code to the signal-sender making it log a message when
an unhandled fatal signal will be delivered.
Signed-of by: Folkert van Heusden <folkert@vanheusden.com
--- kernel/signal.c.org 2007-05-20 22:47:13.000000000 +0200
+++ kernel/signal.c 2007-05-21 14:46:05.000000000 +0200
@@ -739,6 +739,12 @@
struct sigqueue * q = NULL;
int ret = 0;
+ /* unhandled fatal signals are logged */
+ if (sig_fatal(t, sig)) {
+ printk(KERN_INFO "Sig %d sent to %d owned by %d.%d (%s)\n",
+ sig, t->pid, t->uid, t->gid, t->comm);
+ }
+
/*
* fast-pathed signals for kernel-internal things like SIGSTOP
* or SIGKILL.
Folkert van Heusden
--
Temperature outside: 21.437500, temperature livingroom:
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-
New version. This one also informs the user about the sende pid/uid of
the signal (when applicable).
Signed-of by: Folkert van Heusden <folkert@vanheusden.com
--- linux/kernel/signal.c.org 2007-05-20 22:47:13.000000000 +0200
+++ linux/kernel/signal.c 2007-06-10 00:21:31.000000000 +0200
@@ -739,6 +739,18 @@
struct sigqueue * q = NULL;
int ret = 0;
+ /* unhandled fatal signals are logged */
+ if (sig_fatal(t, sig)) {
+ if (is_si_special(info))
+ printk(KERN_INFO "Sig %d sent to %d owned by %d.%d (%s)\n",
+ sig, t->pid, t->uid, t->gid, t->comm);
+ else
+ printk(KERN_INFO "Sig %d sent to %d owned by %d.%d (%s), sent by pid %d, uid %d\n",
+ sig, t->pid, t->uid, t->gid, t->comm,
+ info -> _sifields._kill._pid,
+ info -> _sifields._kill._uid);
+ }
+
/*
* fast-pathed signals for kernel-internal things like SIGSTOP
* or SIGKILL.
Folkert van Heusden
--
Feeling generous? -> http://www.vanheusden.com/wishlist.php
----------------------------------------------------------------------
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-
Am I the only one whose eyes are hurt by these spaces? -- Jiri Kosina -
They were discussed before already. And they were fixed up (t->uid...). And now new ones got added. Ergh. Jan -- -
Anyway, with print-fatal-signals enabled a user could spam syslogd too, simply with a (char *)0 = 0 program, but we could always identify the spam attempts logging the process uid... In any case, I agree, it should depend on that patch... What about adding a simple msleep_interruptible(SOME_MSECS) at the end of log_vm_enomem() or, at least, a might_sleep() to limit the potential spam/second rate? -Andrea -
An msleep will slow down this process, but do nothing about slowing down the amount of logging. Simply fork a few more processes and all you are doing with msleep is polluting the pid space. What about a throttling similar to what ia64 does for floating point assist faults (handle_fpu_swa()). There is a thread flag to not log the events at all. It is rate throttled globally, but uses per cpu variables for early exits. This algorithm scaled well to a thousand cpus. I think this may be a good fit. Good Luck, Robin -
Actually using printk_ratelimit() should be enough... BTW print_fatal_signals()
should use it too.
-Andrea
---
Signed-off-by: Andrea Righi <a.righi@cineca.it>
diff -urpN linux-2.6.21/mm/mmap.c linux-2.6.21-vm-log-enomem/mm/mmap.c
--- linux-2.6.21/mm/mmap.c 2007-04-26 05:08:32.000000000 +0200
+++ linux-2.6.21-vm-log-enomem/mm/mmap.c 2007-05-18 17:17:32.000000000 +0200
@@ -77,6 +77,29 @@ int sysctl_max_map_count __read_mostly =
atomic_t vm_committed_space = ATOMIC_INIT(0);
/*
+ * Print current process informations when it fails to allocate new virtual
+ * memory.
+ */
+static inline void log_vm_enomem(void)
+{
+ unsigned long total_vm = 0;
+ struct mm_struct *mm;
+
+ if (unlikely(!printk_ratelimit()))
+ return;
+
+ task_lock(current);
+ mm = current->mm;
+ if (mm)
+ total_vm = mm->total_vm;
+ task_unlock(current);
+
+ printk(KERN_INFO
+ "out of virtual memory for process %d (%s): total_vm=%lu, uid=%d\n",
+ current->pid, current->comm, total_vm, current->uid);
+}
+
+/*
* Check that a process has enough memory to allocate a new virtual
* mapping. 0 means there is enough memory for the allocation to
* succeed and -ENOMEM implies there is not.
@@ -175,6 +198,7 @@ int __vm_enough_memory(long pages, int c
return 0;
error:
vm_unacct_memory(pages);
+ log_vm_enomem();
return -ENOMEM;
}
-
I mean, something like this...
---
Limit the rate of the printk()s in print_fatal_signal() to avoid potential DoS
problems.
Signed-off-by: Andrea Righi <a.righi@cineca.it>
diff -urpN linux-2.6.22-rc1-mm1/kernel/signal.c linux-2.6.22-rc1-mm1-limit-print_fatal_signals-rate/kernel/signal.c
--- linux-2.6.22-rc1-mm1/kernel/signal.c 2007-05-18 17:48:55.000000000 +0200
+++ linux-2.6.22-rc1-mm1-limit-print_fatal_signals-rate/kernel/signal.c 2007-05-18 17:58:13.000000000 +0200
@@ -790,6 +790,9 @@ static void print_vmas(void)
static void print_fatal_signal(struct pt_regs *regs, int signr)
{
+ if (unlikely(!printk_ratelimit()))
+ return;
+
printk("%s/%d: potentially unexpected fatal signal %d.\n",
current->comm, current->pid, signr);
-
can we have both KERN_WARNING please? Gruss Bernd -
Depends on print_fatal_signals patch.
---
Limit the rate of print_fatal_signal() to avoid potential denial-of-service
attacks.
Signed-off-by: Andrea Righi <a.righi@cineca.it>
diff -urpN linux-2.6.22-rc1-mm1/kernel/signal.c linux-2.6.22-rc1-mm1-vm-log-enomem/kernel/signal.c
--- linux-2.6.22-rc1-mm1/kernel/signal.c 2007-05-19 11:25:24.000000000 +0200
+++ linux-2.6.22-rc1-mm1-vm-log-enomem/kernel/signal.c 2007-05-19 11:30:00.000000000 +0200
@@ -790,7 +790,10 @@ static void print_vmas(void)
static void print_fatal_signal(struct pt_regs *regs, int signr)
{
- printk("%s/%d: potentially unexpected fatal signal %d.\n",
+ if (unlikely(!printk_ratelimit()))
+ return;
+
+ printk(KERN_WARNING "%s/%d: potentially unexpected fatal signal %d.\n",
current->comm, current->pid, signr);
#ifdef __i386__
-
Well OK. But vdso-print-fatal-signals.patch is designated not-for-mainline anyway. I think the DoS which you identify has been available for a very long time on ia64, x86_64 and perhaps others. -
For the mainline a fix could be the following...
---
Limit the rate of the kernel logging for the segfaults of user applications, to
avoid potential message floods or denial-of-service attacks.
Signed-off-by: Andrea Righi <a.righi@cineca.it>
diff -urpN linux-2.6.22-rc2/arch/avr32/mm/fault.c linux-2.6.22-rc2-limit-segfaults-printk-rate/arch/avr32/mm/fault.c
--- linux-2.6.22-rc2/arch/avr32/mm/fault.c 2007-05-19 13:11:30.000000000 +0200
+++ linux-2.6.22-rc2-limit-segfaults-printk-rate/arch/avr32/mm/fault.c 2007-05-21 11:48:37.000000000 +0200
@@ -158,7 +158,7 @@ bad_area:
up_read(&mm->mmap_sem);
if (user_mode(regs)) {
- if (exception_trace)
+ if (exception_trace && printk_ratelimit())
printk("%s%s[%d]: segfault at %08lx pc %08lx "
"sp %08lx ecr %lu\n",
is_init(tsk) ? KERN_EMERG : KERN_INFO,
diff -urpN linux-2.6.22-rc2/arch/x86_64/mm/fault.c linux-2.6.22-rc2-limit-segfaults-printk-rate/arch/x86_64/mm/fault.c
--- linux-2.6.22-rc2/arch/x86_64/mm/fault.c 2007-05-21 11:42:07.000000000 +0200
+++ linux-2.6.22-rc2-limit-segfaults-printk-rate/arch/x86_64/mm/fault.c 2007-05-21 11:45:55.000000000 +0200
@@ -489,7 +489,8 @@ bad_area_nosemaphore:
(address >> 32))
return;
- if (exception_trace && unhandled_signal(tsk, SIGSEGV)) {
+ if (exception_trace && unhandled_signal(tsk, SIGSEGV) &&
+ printk_ratelimit()) {
printk(
"%s%s[%d]: segfault at %016lx rip %016lx rsp %016lx error %lx\n",
tsk->pid > 1 ? KERN_INFO : KERN_EMERG,
-
btw., why? It's very, very useful to distro, early-boot-userspace and glibc development. The only add-on change should be to not print SIGKILL events. Otherwise it's very much a keeper. Hm? Ingo -
err, because that's what I decided a year ago. I wonder why ;) Perhaps because of the DoS thing, but it has a /proc knob and defaults to <promotes it> -
yeah. There's also a boot option. To address the DoS angle, should i make it optionally printk_ratelimit() perhaps? (although often the thanks :-) Ingo -
I don't think so, really. It takes a deliberate act to turn the thing on, after all. I we _were_ concerned about the logspam then it might be better to make the feature turn itself off after 100 messages, rather than ratelimiting it. -
Actually it seems that SIGKILLs are not printed. In get_signal_to_deliver() we have:
[snip]
@@ -1843,6 +1879,8 @@ relock:
* Anything else is fatal, maybe with a core dump.
*/
current->flags |= PF_SIGNALED;
+ if ((signr != SIGKILL) && print_fatal_signals)
+ print_fatal_signal(regs, signr);
if (sig_kernel_coredump(signr)) {
/*
* If it was able to dump core, this kills all
[snip]
-Andrea
-
yeah. Either i implemented that and forgot, or someone else implemented it. :) Ingo -
ah, that's already included in the version in -mm. admittedly, the #ifdef __i386__ is quite lame, but there's no generic safely-try-to-show-code-at-addr function available at the moment. Ingo -
And align this one with the print_fatal layout:
printk(KERN_WARNING
"%s/%d process cannot request more virtual memory: total_vm=%lu, uid=%d\n",
current->comm, current->pid, total_vm, current->uid);
Greetings
Bernd
-
Depends on print_fatal_signals patch.
---
Print informations about userspace processes that fail to allocate new virtual
memory.
Signed-off-by: Andrea Righi <a.righi@cineca.it>
diff -urpN linux-2.6.22-rc1-mm1/mm/mmap.c linux-2.6.22-rc1-mm1-vm-log-enomem/mm/mmap.c
--- linux-2.6.22-rc1-mm1/mm/mmap.c 2007-05-19 11:25:24.000000000 +0200
+++ linux-2.6.22-rc1-mm1-vm-log-enomem/mm/mmap.c 2007-05-19 11:55:05.000000000 +0200
@@ -77,6 +77,31 @@ int sysctl_overcommit_ratio = 50; /* def
int sysctl_max_map_count __read_mostly = DEFAULT_MAX_MAP_COUNT;
atomic_t vm_committed_space = ATOMIC_INIT(0);
+extern int print_fatal_signals;
+
+/*
+ * Print current process informations when it fails to allocate new virtual
+ * memory.
+ */
+static inline void log_vm_enomem(void)
+{
+ unsigned long total_vm = 0;
+ struct mm_struct *mm;
+
+ if (unlikely(!printk_ratelimit()))
+ return;
+
+ task_lock(current);
+ mm = current->mm;
+ if (mm)
+ total_vm = mm->total_vm;
+ task_unlock(current);
+
+ printk(KERN_WARNING
+ "%s/%d process cannot request more virtual memory: total_vm=%lu, uid=%d\n",
+ current->comm, current->pid, total_vm, current->uid);
+}
+
/*
* Check that a process has enough memory to allocate a new virtual
* mapping. 0 means there is enough memory for the allocation to
@@ -177,6 +202,9 @@ int __vm_enough_memory(long pages, int c
error:
vm_unacct_memory(pages);
+ if (print_fatal_signals)
+ log_vm_enomem();
+
return -ENOMEM;
}
-
Why is this useful? -
Well... in strict overcommit mode (overcommit_memory=2) this is the only way to track down problems of the (bad-designed) user applications that exit when they receive a -ENOMEM without logging anything... and, anyway, it could be an additional aid in figuring out what is going wrong on inside a system. BTW, I don't think it should be enabled by default, so this is the reason why it should depend on print_fatal_signals patch. -Andrea -
Yeah well it's all captured by syslogd/klogd and written to a file and diskspace is cheap. Folkert van Heusden -- Feeling generous? -> http://www.vanheusden.com/wishlist.php ---------------------------------------------------------------------- Phone: +31-6-41278122, PGP-key: 1F28D8AE, www.vanheusden.com -
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git: | |
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