Messages in this thread | | | Date | Wed, 16 Jan 2013 03:07:53 +0100 | From | Jan Kara <> | Subject | Re: [PATCH v2] writeback: mark sysctl vm.block_dump for removal |
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On Tue 15-01-13 08:28:13, Tejun Heo wrote: > vm.block_dump is nasty in that it dumps IO traces directly to printk. > It isn't scalable and can easily lead to looping behavior - IO > generating kernel message which in turn genreates log IO, ad > infinitum. > > Now that proper tracepoints are in place, vm.block_dump isn't > necessary. Generate a warning if used so that it can be removed down > the road. > > Cc: Added contact info as suggested by Jan. > > Signed-off-by: Tejun Heo <tj@kernel.org> > Cc: Jan Kara <jack@suse.cz> Thanks. The patch looks good. You can add: Reviewed-by: Jan Kara <jack@suse.cz>
Honza > --- > include/linux/writeback.h | 3 +++ > kernel/sysctl.c | 2 +- > mm/page-writeback.c | 15 +++++++++++++++ > patches/series | 1 + > 4 files changed, 20 insertions(+), 1 deletion(-) > > diff --git a/include/linux/writeback.h b/include/linux/writeback.h > index b82a83a..678ee6d 100644 > --- a/include/linux/writeback.h > +++ b/include/linux/writeback.h > @@ -143,6 +143,9 @@ extern int dirty_ratio_handler(struct ctl_table *table, int write, > extern int dirty_bytes_handler(struct ctl_table *table, int write, > void __user *buffer, size_t *lenp, > loff_t *ppos); > +extern int block_dump_handler(struct ctl_table *table, int write, > + void __user *buffer, size_t *lenp, > + loff_t *ppos); > > struct ctl_table; > int dirty_writeback_centisecs_handler(struct ctl_table *, int, > diff --git a/kernel/sysctl.c b/kernel/sysctl.c > index c88878d..9e7f7b5 100644 > --- a/kernel/sysctl.c > +++ b/kernel/sysctl.c > @@ -1288,7 +1288,7 @@ static struct ctl_table vm_table[] = { > .data = &block_dump, > .maxlen = sizeof(block_dump), > .mode = 0644, > - .proc_handler = proc_dointvec, > + .proc_handler = block_dump_handler, > .extra1 = &zero, > }, > { > diff --git a/mm/page-writeback.c b/mm/page-writeback.c > index 6f42712..605632d 100644 > --- a/mm/page-writeback.c > +++ b/mm/page-writeback.c > @@ -390,6 +390,21 @@ int dirty_bytes_handler(struct ctl_table *table, int write, > return ret; > } > > +int block_dump_handler(struct ctl_table *table, int write, > + void __user *buffer, size_t *lenp, loff_t *ppos) > +{ > + static bool warned = false; > + int ret; > + > + ret = proc_dointvec(table, write, buffer, lenp, ppos); > + if (!warned && block_dump) { > + pr_warning("sysctl: vm.block_dump is scheduled for removal. Use tracepoints instead.\n"); > + pr_warning("sysctl: Please contact Jens Axboe <axboe@kernel.dk> if you require this.\n"); > + warned = true; > + } > + return ret; > +} > + > static unsigned long wp_next_time(unsigned long cur_time) > { > cur_time += VM_COMPLETIONS_PERIOD_LEN; > diff --git a/patches/series b/patches/series > index 9fb9bfe..b2582cb 100644 > --- a/patches/series > +++ b/patches/series > @@ -18,3 +18,4 @@ kill-pool-gcwq > remove-gcwq > rename-nr_running > cleanup-leftovers > +dbg -- Jan Kara <jack@suse.cz> SUSE Labs, CR
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