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 <t...@kernel.org>
> Cc: Jan Kara <j...@suse.cz>
Thanks. The patch looks good. You can add:
Reviewed-by: Jan Kara <j...@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 <ax...@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 <j...@suse.cz>
SUSE Labs, CR
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