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2007-07-17Freezer: make kernel threads nonfreezable by defaultRafael J. Wysocki
Currently, the freezer treats all tasks as freezable, except for the kernel threads that explicitly set the PF_NOFREEZE flag for themselves. This approach is problematic, since it requires every kernel thread to either set PF_NOFREEZE explicitly, or call try_to_freeze(), even if it doesn't care for the freezing of tasks at all. It seems better to only require the kernel threads that want to or need to be frozen to use some freezer-related code and to remove any freezer-related code from the other (nonfreezable) kernel threads, which is done in this patch. The patch causes all kernel threads to be nonfreezable by default (ie. to have PF_NOFREEZE set by default) and introduces the set_freezable() function that should be called by the freezable kernel threads in order to unset PF_NOFREEZE. It also makes all of the currently freezable kernel threads call set_freezable(), so it shouldn't cause any (intentional) change of behaviour to appear. Additionally, it updates documentation to describe the freezing of tasks more accurately. [akpm@linux-foundation.org: build fixes] Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Acked-by: Nigel Cunningham <nigel@nigel.suspend2.net> Cc: Pavel Machek <pavel@ucw.cz> Cc: Oleg Nesterov <oleg@tv-sign.ru> Cc: Gautham R Shenoy <ego@in.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2006-12-07[PATCH] Add include/linux/freezer.h and move definitions from sched.hNigel Cunningham
Move process freezing functions from include/linux/sched.h to freezer.h, so that modifications to the freezer or the kernel configuration don't require recompiling just about everything. [akpm@osdl.org: fix ueagle driver] Signed-off-by: Nigel Cunningham <nigel@suspend2.net> Cc: "Rafael J. Wysocki" <rjw@sisk.pl> Cc: Pavel Machek <pavel@ucw.cz> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-25[PATCH] pdflush: handle resume wakeupsAndrew Morton
pdflush is carefully designed to ensure that all wakeups have some corresponding work to do - if a woken-up pdflush thread discovers that it hasn't been given any work to do then this is considered an error. That all broke when swsusp came along - because a timer-delivered wakeup to a frozen pdflush thread will just get lost. This causes the pdflush thread to get lost as well: the writeback timer is supposed to be re-armed by pdflush in process context, but pdflush doesn't execute the callout which does this. Fix that up by ignoring the return value from try_to_freeze(): jsut proceed, see if we have any work pending and only go back to sleep if that is not the case. Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23[PATCH] More BUG_ON conversionEric Sesterhenn
Signed-off-by: Eric Sesterhenn <snakebyte@gmx.de> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Cc: Bartlomiej Zolnierkiewicz <B.Zolnierkiewicz@elka.pw.edu.pl> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: James Bottomley <James.Bottomley@steeleye.com> Acked-by: "Salyzyn, Mark" <mark_salyzyn@adaptec.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08[PATCH] Swap Migration V5: PF_SWAPWRITE to allow writing to swapChristoph Lameter
Add PF_SWAPWRITE to control a processes permission to write to swap. - Use PF_SWAPWRITE in may_write_to_queue() instead of checking for kswapd and pdflush - Set PF_SWAPWRITE flag for kswapd and pdflush Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-30[PATCH] cpusets: confine pdflush to its cpusetPaul Jackson
This patch keeps pdflush daemons on the same cpuset as their parent, the kthread daemon. Some large NUMA configurations put as much as they can of kernel threads and other classic Unix load in what's called a bootcpuset, keeping the rest of the system free for dedicated jobs. This effort is thwarted by pdflush, which dynamically destroys and recreates pdflush daemons depending on load. It's easy enough to force the originally created pdflush deamons into the bootcpuset, at system boottime. But the pdflush threads created later were allowed to run freely across the system, due to the necessary line in their startup kthread(): set_cpus_allowed(current, CPU_MASK_ALL); By simply coding pdflush to start its threads with the cpus_allowed restrictions of its cpuset (inherited from kthread, its parent) we can ensure that dynamically created pdflush threads are also kept in the bootcpuset. On systems w/o cpusets, or w/o a bootcpuset implementation, the following will have no affect, leaving pdflush to run on any CPU, as before. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-25[PATCH] Cleanup patch for process freezingChristoph Lameter
1. Establish a simple API for process freezing defined in linux/include/sched.h: frozen(process) Check for frozen process freezing(process) Check if a process is being frozen freeze(process) Tell a process to freeze (go to refrigerator) thaw_process(process) Restart process frozen_process(process) Process is frozen now 2. Remove all references to PF_FREEZE and PF_FROZEN from all kernel sources except sched.h 3. Fix numerous locations where try_to_freeze is manually done by a driver 4. Remove the argument that is no longer necessary from two function calls. 5. Some whitespace cleanup 6. Clear potential race in refrigerator (provides an open window of PF_FREEZE cleared before setting PF_FROZEN, recalc_sigpending does not check PF_FROZEN). This patch does not address the problem of freeze_processes() violating the rule that a task may only modify its own flags by setting PF_FREEZE. This is not clean in an SMP environment. freeze(process) is therefore not SMP safe! Signed-off-by: Christoph Lameter <christoph@lameter.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-16Linux-2.6.12-rc2Linus Torvalds
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!