| Message ID | 20200119030636.11899-2-richardw.yang@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | mm/migrate.c: cleanup on do_pages_move() | expand |
On Sun 19-01-20 11:06:29, Wei Yang wrote: > Before move page to target node, we would check if the node id is valid. > In case we would try to move pages to the same target node, it is not > necessary to do the check each time. > > This patch tries to skip the check if the node has been checked. > > Signed-off-by: Wei Yang <richardw.yang@linux.intel.com> > --- > mm/migrate.c | 19 +++++++++++-------- > 1 file changed, 11 insertions(+), 8 deletions(-) > > diff --git a/mm/migrate.c b/mm/migrate.c > index 430fdccc733e..ba7cf4fa43a0 100644 > --- a/mm/migrate.c > +++ b/mm/migrate.c > @@ -1612,15 +1612,18 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, > goto out_flush; > addr = (unsigned long)untagged_addr(p); > > - err = -ENODEV; > - if (node < 0 || node >= MAX_NUMNODES) > - goto out_flush; > - if (!node_state(node, N_MEMORY)) > - goto out_flush; > + /* Check node if it is not checked. */ > + if (current_node == NUMA_NO_NODE || node != current_node) { > + err = -ENODEV; > + if (node < 0 || node >= MAX_NUMNODES) > + goto out_flush; > + if (!node_state(node, N_MEMORY)) > + goto out_flush; This makes the code harder to read IMHO. The original code checks the valid node first and it doesn't conflate that with the node caching logic which your change does. > > - err = -EACCES; > - if (!node_isset(node, task_nodes)) > - goto out_flush; > + err = -EACCES; > + if (!node_isset(node, task_nodes)) > + goto out_flush; > + } > > if (current_node == NUMA_NO_NODE) { > current_node = node; > -- > 2.17.1
On Mon, Jan 20, 2020 at 10:36:46AM +0100, Michal Hocko wrote: >On Sun 19-01-20 11:06:29, Wei Yang wrote: >> Before move page to target node, we would check if the node id is valid. >> In case we would try to move pages to the same target node, it is not >> necessary to do the check each time. >> >> This patch tries to skip the check if the node has been checked. >> >> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com> >> --- >> mm/migrate.c | 19 +++++++++++-------- >> 1 file changed, 11 insertions(+), 8 deletions(-) >> >> diff --git a/mm/migrate.c b/mm/migrate.c >> index 430fdccc733e..ba7cf4fa43a0 100644 >> --- a/mm/migrate.c >> +++ b/mm/migrate.c >> @@ -1612,15 +1612,18 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, >> goto out_flush; >> addr = (unsigned long)untagged_addr(p); >> >> - err = -ENODEV; >> - if (node < 0 || node >= MAX_NUMNODES) >> - goto out_flush; >> - if (!node_state(node, N_MEMORY)) >> - goto out_flush; >> + /* Check node if it is not checked. */ >> + if (current_node == NUMA_NO_NODE || node != current_node) { >> + err = -ENODEV; >> + if (node < 0 || node >= MAX_NUMNODES) >> + goto out_flush; >> + if (!node_state(node, N_MEMORY)) >> + goto out_flush; > >This makes the code harder to read IMHO. The original code checks the >valid node first and it doesn't conflate that with the node caching >logic which your change does. > I am sorry, would you mind showing me an example about the conflate in my change? I don't get it. >> >> - err = -EACCES; >> - if (!node_isset(node, task_nodes)) >> - goto out_flush; >> + err = -EACCES; >> + if (!node_isset(node, task_nodes)) >> + goto out_flush; >> + } >> >> if (current_node == NUMA_NO_NODE) { >> current_node = node; >> -- >> 2.17.1 > >-- >Michal Hocko >SUSE Labs
On Tue 21-01-20 06:25:40, Wei Yang wrote: > On Mon, Jan 20, 2020 at 10:36:46AM +0100, Michal Hocko wrote: > >On Sun 19-01-20 11:06:29, Wei Yang wrote: > >> Before move page to target node, we would check if the node id is valid. > >> In case we would try to move pages to the same target node, it is not > >> necessary to do the check each time. > >> > >> This patch tries to skip the check if the node has been checked. > >> > >> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com> > >> --- > >> mm/migrate.c | 19 +++++++++++-------- > >> 1 file changed, 11 insertions(+), 8 deletions(-) > >> > >> diff --git a/mm/migrate.c b/mm/migrate.c > >> index 430fdccc733e..ba7cf4fa43a0 100644 > >> --- a/mm/migrate.c > >> +++ b/mm/migrate.c > >> @@ -1612,15 +1612,18 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, > >> goto out_flush; > >> addr = (unsigned long)untagged_addr(p); > >> > >> - err = -ENODEV; > >> - if (node < 0 || node >= MAX_NUMNODES) > >> - goto out_flush; > >> - if (!node_state(node, N_MEMORY)) > >> - goto out_flush; > >> + /* Check node if it is not checked. */ > >> + if (current_node == NUMA_NO_NODE || node != current_node) { > >> + err = -ENODEV; > >> + if (node < 0 || node >= MAX_NUMNODES) > >> + goto out_flush; > >> + if (!node_state(node, N_MEMORY)) > >> + goto out_flush; > > > >This makes the code harder to read IMHO. The original code checks the > >valid node first and it doesn't conflate that with the node caching > >logic which your change does. > > > > I am sorry, would you mind showing me an example about the conflate in my > change? I don't get it. NUMA_NO_NODE is the iteration logic, right? It resets the batching node. Node check read from the userspace is an input sanitization. Do not put those two into the same checks. More clear now?
On Tue, Jan 21, 2020 at 09:42:05AM +0100, Michal Hocko wrote: >On Tue 21-01-20 06:25:40, Wei Yang wrote: >> On Mon, Jan 20, 2020 at 10:36:46AM +0100, Michal Hocko wrote: >> >On Sun 19-01-20 11:06:29, Wei Yang wrote: >> >> Before move page to target node, we would check if the node id is valid. >> >> In case we would try to move pages to the same target node, it is not >> >> necessary to do the check each time. >> >> >> >> This patch tries to skip the check if the node has been checked. >> >> >> >> Signed-off-by: Wei Yang <richardw.yang@linux.intel.com> >> >> --- >> >> mm/migrate.c | 19 +++++++++++-------- >> >> 1 file changed, 11 insertions(+), 8 deletions(-) >> >> >> >> diff --git a/mm/migrate.c b/mm/migrate.c >> >> index 430fdccc733e..ba7cf4fa43a0 100644 >> >> --- a/mm/migrate.c >> >> +++ b/mm/migrate.c >> >> @@ -1612,15 +1612,18 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, >> >> goto out_flush; >> >> addr = (unsigned long)untagged_addr(p); >> >> >> >> - err = -ENODEV; >> >> - if (node < 0 || node >= MAX_NUMNODES) >> >> - goto out_flush; >> >> - if (!node_state(node, N_MEMORY)) >> >> - goto out_flush; >> >> + /* Check node if it is not checked. */ >> >> + if (current_node == NUMA_NO_NODE || node != current_node) { >> >> + err = -ENODEV; >> >> + if (node < 0 || node >= MAX_NUMNODES) >> >> + goto out_flush; >> >> + if (!node_state(node, N_MEMORY)) >> >> + goto out_flush; >> > >> >This makes the code harder to read IMHO. The original code checks the >> >valid node first and it doesn't conflate that with the node caching >> >logic which your change does. >> > >> >> I am sorry, would you mind showing me an example about the conflate in my >> change? I don't get it. > >NUMA_NO_NODE is the iteration logic, right? It resets the batching node. >Node check read from the userspace is an input sanitization. Do not put >those two into the same checks. More clear now? Yes, I see your point. Can we think like this: On each iteration, we do an input sanitization? Well, this is a trivial one. If you don't like it, I would remove this. >-- >Michal Hocko >SUSE Labs
On Wed 22-01-20 08:36:50, Wei Yang wrote:
[...]
> Well, this is a trivial one. If you don't like it, I would remove this.
Yes, please drop it. Thanks!
diff --git a/mm/migrate.c b/mm/migrate.c index 430fdccc733e..ba7cf4fa43a0 100644 --- a/mm/migrate.c +++ b/mm/migrate.c @@ -1612,15 +1612,18 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes, goto out_flush; addr = (unsigned long)untagged_addr(p); - err = -ENODEV; - if (node < 0 || node >= MAX_NUMNODES) - goto out_flush; - if (!node_state(node, N_MEMORY)) - goto out_flush; + /* Check node if it is not checked. */ + if (current_node == NUMA_NO_NODE || node != current_node) { + err = -ENODEV; + if (node < 0 || node >= MAX_NUMNODES) + goto out_flush; + if (!node_state(node, N_MEMORY)) + goto out_flush; - err = -EACCES; - if (!node_isset(node, task_nodes)) - goto out_flush; + err = -EACCES; + if (!node_isset(node, task_nodes)) + goto out_flush; + } if (current_node == NUMA_NO_NODE) { current_node = node;
Before move page to target node, we would check if the node id is valid. In case we would try to move pages to the same target node, it is not necessary to do the check each time. This patch tries to skip the check if the node has been checked. Signed-off-by: Wei Yang <richardw.yang@linux.intel.com> --- mm/migrate.c | 19 +++++++++++-------- 1 file changed, 11 insertions(+), 8 deletions(-)