Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761945AbXE1Jqr (ORCPT ); Mon, 28 May 2007 05:46:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754232AbXE1Jqj (ORCPT ); Mon, 28 May 2007 05:46:39 -0400 Received: from nigel.suspend2.net ([203.171.70.205]:36122 "EHLO nigel.suspend2.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756877AbXE1Jqj (ORCPT ); Mon, 28 May 2007 05:46:39 -0400 Subject: Re: [RFC][PATCH][EXPERIMENTAL] Make kernel threads nonfreezable by default From: Nigel Cunningham Reply-To: nigel@nigel.suspend2.net To: "Rafael J. Wysocki" Cc: LKML , Andrew Morton , Gautham R Shenoy , Linus Torvalds , Oleg Nesterov , Pavel Machek In-Reply-To: <200705270012.59177.rjw@sisk.pl> References: <200705270012.59177.rjw@sisk.pl> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-j9AQUlhqS4b15JbYm4uJ" Date: Mon, 28 May 2007 19:46:36 +1000 Message-Id: <1180345596.14749.40.camel@nigel.suspend2.net> Mime-Version: 1.0 X-Mailer: Evolution 2.10.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6168 Lines: 168 --=-j9AQUlhqS4b15JbYm4uJ Content-Type: text/plain Content-Transfer-Encoding: quoted-printable Hello! In reply to your more recent message, I had looked but not tried, so didn't feel in a position to reply yet. On Sun, 2007-05-27 at 00:12 +0200, Rafael J. Wysocki wrote: > 63 files changed, 78 insertions(+), 138 deletions(-) Well, that looks good, for a start :) > Index: linux-2.6.22-rc3/kernel/exit.c > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > --- linux-2.6.22-rc3.orig/kernel/exit.c > +++ linux-2.6.22-rc3/kernel/exit.c > @@ -389,6 +389,11 @@ void daemonize(const char *name, ...) > * they would be locked into memory. > */ > exit_mm(current); > + /* > + * We don't want to have TIF_FREEZE set if the system-wide hibernation > + * or suspend transision begins right now. > + */ > + current->flags |=3D PF_NOFREEZE; s/transision/transition =20 > set_special_pids(1, 1); > proc_clear_tty(current); > Index: linux-2.6.22-rc3/include/linux/freezer.h > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > --- linux-2.6.22-rc3.orig/include/linux/freezer.h > +++ linux-2.6.22-rc3/include/linux/freezer.h > @@ -118,6 +118,14 @@ static inline int freezer_should_skip(st > return !!(p->flags & PF_FREEZER_SKIP); > } > =20 > +/* > + * Tell the freezer that the current task should be frozen by it > + */ > +static inline void set_freezable(void) > +{ > + current->flags &=3D ~PF_NOFREEZE; > +} > + Given the clearing of the flag above, should we just have a set_unfreezeable here that's used above (and potentially elsewhere)... (reads more)... or more generic set_[un]freezeable(task_struct *p) routines that could also be used in copy_flags below? > #else > static inline int frozen(struct task_struct *p) { return 0; } > static inline int freezing(struct task_struct *p) { return 0; } > @@ -134,6 +142,7 @@ static inline int try_to_freeze(void) {=20 > static inline void freezer_do_not_count(void) {} > static inline void freezer_count(void) {} > static inline int freezer_should_skip(struct task_struct *p) { return 0;= } > +static inline void set_freezable_current(void) {} > #endif > =20 > #endif /* LINUX_FREEZER_H */ > Index: linux-2.6.22-rc3/kernel/fork.c > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > --- linux-2.6.22-rc3.orig/kernel/fork.c > +++ linux-2.6.22-rc3/kernel/fork.c > @@ -920,7 +920,7 @@ static inline void copy_flags(unsigned l > { > unsigned long new_flags =3D p->flags; > =20 > - new_flags &=3D ~(PF_SUPERPRIV | PF_NOFREEZE); > + new_flags &=3D ~PF_SUPERPRIV; > new_flags |=3D PF_FORKNOEXEC; > if (!(clone_flags & CLONE_PTRACE)) > p->ptrace =3D 0; > Index: linux-2.6.22-rc3/arch/i386/kernel/io_apic.c > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > --- linux-2.6.22-rc3.orig/arch/i386/kernel/io_apic.c > +++ linux-2.6.22-rc3/arch/i386/kernel/io_apic.c > @@ -669,7 +669,6 @@ static int balanced_irq(void *unused) > =20 > for ( ; ; ) { > time_remaining =3D schedule_timeout_interruptible(time_remaining); > - try_to_freeze(); > if (time_after(jiffies, > prev_balance_time+balanced_irq_interval)) { > preempt_disable(); I'm the one who is confused, aren't I? If I'm reading this right, io_apic used to be frozen. After this patch, it will not be frozen. If that's the intended behaviour, shouldn't this be two patches - one to make kernel threads unfreezeable by default, and one to make threads that were formerly freezeable unfreezeable? [...] > Index: linux-2.6.22-rc3/Documentation/power/swsusp.txt > =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D > --- linux-2.6.22-rc3.orig/Documentation/power/swsusp.txt > +++ linux-2.6.22-rc3/Documentation/power/swsusp.txt > @@ -140,22 +140,6 @@ should be sent to the mailing list avail > website, and not to the Linux Kernel Mailing List. We are working > toward merging suspend2 into the mainline kernel. > =20 > -Q: A kernel thread must voluntarily freeze itself (call 'refrigerator'). > -I found some kernel threads that don't do it, and they don't freeze > -so the system can't sleep. Is this a known behavior? > - > -A: All such kernel threads need to be fixed, one by one. Select the > -place where the thread is safe to be frozen (no kernel semaphores > -should be held at that point and it must be safe to sleep there), and > -add: > - > - try_to_freeze(); > - > -If the thread is needed for writing the image to storage, you should > -instead set the PF_NOFREEZE process flag when creating the thread (and > -be very careful). > - > - > Q: What is the difference between "platform" and "shutdown"? > =20 > A: Perhaps it would be good to keep a variant of this question, along the lines of: Q: I have a kernel thread that needs to be frozen during hibernation. How do I make that happen? Regards, Nigel --=-j9AQUlhqS4b15JbYm4uJ Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQBGWqT8N0y+n1M3mo0RAvSuAKDJOuqwx/s35c9TdjD4zzdriheJFQCfWFCP H/tSW7tbydsFLUSIiIcGXUU= =XYYM -----END PGP SIGNATURE----- --=-j9AQUlhqS4b15JbYm4uJ-- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/