path: root/init
diff options
authorLinus Torvalds <torvalds@linux-foundation.org>2012-05-21 12:52:42 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-05-21 12:52:42 -0700
commit31a67102f4762df5544bc2dfb34a931233d2a5b2 (patch)
tree5ab348c520d60e331fb9e469cd592ee411f3850f /init
parentnet: drop NET dependency from HAVE_BPF_JIT (diff)
Fix blocking allocations called very early during bootup
During early boot, when the scheduler hasn't really been fully set up, we really can't do blocking allocations because with certain (dubious) configurations the "might_resched()" calls can actually result in scheduling events. We could just make such users always use GFP_ATOMIC, but quite often the code that does the allocation isn't really aware of the fact that the scheduler isn't up yet, and forcing that kind of random knowledge on the initialization code is just annoying and not good for anybody. And we actually have a the 'gfp_allowed_mask' exactly for this reason: it's just that the kernel init sequence happens to set it to allow blocking allocations much too early. So move the 'gfp_allowed_mask' initialization from 'start_kernel()' (which is some of the earliest init code, and runs with preemption disabled for good reasons) into 'kernel_init()'. kernel_init() is run in the newly created thread that will become the 'init' process, as opposed to the early startup code that runs within the context of what will be the first idle thread. So by the time we reach 'kernel_init()', we know that the scheduler must be at least limping along, because we've already scheduled from the idle thread into the init thread. Reported-by: Steven Rostedt <rostedt@goodmis.org> Cc: David Rientjes <rientjes@google.com> Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'init')
1 files changed, 4 insertions, 3 deletions
diff --git a/init/main.c b/init/main.c
index 44b2433334c7..cb54cd3dbf05 100644
--- a/init/main.c
+++ b/init/main.c
@@ -560,9 +560,6 @@ asmlinkage void __init start_kernel(void)
early_boot_irqs_disabled = false;
- /* Interrupts are enabled now so all GFP allocations are safe. */
- gfp_allowed_mask = __GFP_BITS_MASK;
@@ -842,6 +839,10 @@ static int __init kernel_init(void * unused)
* Wait until kthreadd is all set-up.
+ /* Now the scheduler is fully set up and can do blocking allocations */
+ gfp_allowed_mask = __GFP_BITS_MASK;
* init can allocate pages on any node