On Wed, Aug 28, 2019 at 12:50 AM Jason Gunthorpe jgg@ziepe.ca wrote:
diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 4fa360a13c1e..82f84cfe372f 100644 +++ b/include/linux/kernel.h @@ -217,7 +217,9 @@ extern void __cant_sleep(const char *file, int line, int preempt_offset);
- might_sleep - annotation for functions that can sleep
- this macro will print a stack trace if it is executed in an atomic
- context (spinlock, irq-handler, ...).
- context (spinlock, irq-handler, ...). Additional sections where blocking is
- not allowed can be annotated with non_block_start() and non_block_end()
- pairs.
- This is a useful debugging help to be able to catch problems early and not
- be bitten later when the calling function happens to sleep when it is not
@@ -233,6 +235,25 @@ extern void __cant_sleep(const char *file, int line, int preempt_offset); # define cant_sleep() \ do { __cant_sleep(__FILE__, __LINE__, 0); } while (0) # define sched_annotate_sleep() (current->task_state_change = 0) +/**
- non_block_start - annotate the start of section where sleeping is prohibited
- This is on behalf of the oom reaper, specifically when it is calling the mmu
- notifiers. The problem is that if the notifier were to block on, for example,
- mutex_lock() and if the process which holds that mutex were to perform a
- sleeping memory allocation, the oom reaper is now blocked on completion of
- that memory allocation. Other blocking calls like wait_event() pose similar
- issues.
- */
+# define non_block_start() \
do { current->non_block_count++; } while (0)+/**
- non_block_end - annotate the end of section where sleeping is prohibited
- Closes a section opened by non_block_start().
- */
+# define non_block_end() \
do { WARN_ON(current->non_block_count-- == 0); } while (0)check-patch does not like these, and I agree
#101: FILE: include/linux/kernel.h:248: +# define non_block_start() \
do { current->non_block_count++; } while (0)/tmp/tmp1spfxufy/0006-kernel-h-Add-non_block_start-end-.patch:108: WARNING: Single statement macros should not use a do {} while (0) loop #108: FILE: include/linux/kernel.h:255: +# define non_block_end() \
do { WARN_ON(current->non_block_count-- == 0); } while (0)Please use a static inline?
We need get_current() plus the task_struct, so this gets real messy real fast. Not even sure which header this would fit in, or whether I'd need to create a new one. You're insisting on this or respinning with the do { } while (0) dropped ok.
Thanks, Daniel
Also, can we get one more ack on this patch?
Jason