| Message ID | 20210312154331.32229-2-mgorman@techsingularity.net (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | Introduce a bulk order-0 page allocator with two in-tree users | expand |
| Context | Check | Description |
|---|---|---|
| netdev/tree_selection | success | Guessing tree name failed - patch did not apply |
On 3/12/21 4:43 PM, Mel Gorman wrote: > __alloc_pages updates GFP flags to enforce what flags are allowed > during a global context such as booting or suspend. This patch moves the > enforcement from __alloc_pages to prepare_alloc_pages so the code can be > shared between the single page allocator and a new bulk page allocator. > > When moving, it is obvious that __alloc_pages() and __alloc_pages > use different names for the same variable. This is an unnecessary > complication so rename gfp_mask to gfp in prepare_alloc_pages() so the > name is consistent. > > No functional change. Hm, I have some doubts. > Signed-off-by: Mel Gorman <mgorman@techsingularity.net> > --- > mm/page_alloc.c | 25 +++++++++++++------------ > 1 file changed, 13 insertions(+), 12 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 00b67c47ad87..f0c1d74ead6f 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -4914,15 +4914,18 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, > return page; > } > > -static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order, > +static inline bool prepare_alloc_pages(gfp_t gfp, unsigned int order, > int preferred_nid, nodemask_t *nodemask, > struct alloc_context *ac, gfp_t *alloc_gfp, > unsigned int *alloc_flags) > { > - ac->highest_zoneidx = gfp_zone(gfp_mask); > - ac->zonelist = node_zonelist(preferred_nid, gfp_mask); > + gfp &= gfp_allowed_mask; > + *alloc_gfp = gfp; > + ... > @@ -4980,8 +4983,6 @@ struct page *__alloc_pages(gfp_t gfp, unsigned int order, int preferred_nid, > return NULL; > } > > - gfp &= gfp_allowed_mask; > - alloc_gfp = gfp; > if (!prepare_alloc_pages(gfp, order, preferred_nid, nodemask, &ac, > &alloc_gfp, &alloc_flags)) > return NULL; As a result, "gfp" doesn't have the restrictions by gfp_allowed_mask applied, only alloc_gfp does. But in case we go to slowpath, before going there we throw away the current alloc_gfp: alloc_gfp = current_gfp_context(gfp); ... page = __alloc_pages_slowpath(alloc_gfp, ...); So we lost the gfp_allowed_mask restrictions here?
On Fri, Mar 19, 2021 at 05:11:39PM +0100, Vlastimil Babka wrote: > On 3/12/21 4:43 PM, Mel Gorman wrote: > > __alloc_pages updates GFP flags to enforce what flags are allowed > > during a global context such as booting or suspend. This patch moves the > > enforcement from __alloc_pages to prepare_alloc_pages so the code can be > > shared between the single page allocator and a new bulk page allocator. > > > > When moving, it is obvious that __alloc_pages() and __alloc_pages > > use different names for the same variable. This is an unnecessary > > complication so rename gfp_mask to gfp in prepare_alloc_pages() so the > > name is consistent. > > > > No functional change. > > Hm, I have some doubts. > And you were right, I'll drop the patch and apply the same mask to the bulk allocator.
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 00b67c47ad87..f0c1d74ead6f 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -4914,15 +4914,18 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, return page; } -static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order, +static inline bool prepare_alloc_pages(gfp_t gfp, unsigned int order, int preferred_nid, nodemask_t *nodemask, struct alloc_context *ac, gfp_t *alloc_gfp, unsigned int *alloc_flags) { - ac->highest_zoneidx = gfp_zone(gfp_mask); - ac->zonelist = node_zonelist(preferred_nid, gfp_mask); + gfp &= gfp_allowed_mask; + *alloc_gfp = gfp; + + ac->highest_zoneidx = gfp_zone(gfp); + ac->zonelist = node_zonelist(preferred_nid, gfp); ac->nodemask = nodemask; - ac->migratetype = gfp_migratetype(gfp_mask); + ac->migratetype = gfp_migratetype(gfp); if (cpusets_enabled()) { *alloc_gfp |= __GFP_HARDWALL; @@ -4936,18 +4939,18 @@ static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order, *alloc_flags |= ALLOC_CPUSET; } - fs_reclaim_acquire(gfp_mask); - fs_reclaim_release(gfp_mask); + fs_reclaim_acquire(gfp); + fs_reclaim_release(gfp); - might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM); + might_sleep_if(gfp & __GFP_DIRECT_RECLAIM); - if (should_fail_alloc_page(gfp_mask, order)) + if (should_fail_alloc_page(gfp, order)) return false; - *alloc_flags = current_alloc_flags(gfp_mask, *alloc_flags); + *alloc_flags = current_alloc_flags(gfp, *alloc_flags); /* Dirty zone balancing only done in the fast path */ - ac->spread_dirty_pages = (gfp_mask & __GFP_WRITE); + ac->spread_dirty_pages = (gfp & __GFP_WRITE); /* * The preferred zone is used for statistics but crucially it is @@ -4980,8 +4983,6 @@ struct page *__alloc_pages(gfp_t gfp, unsigned int order, int preferred_nid, return NULL; } - gfp &= gfp_allowed_mask; - alloc_gfp = gfp; if (!prepare_alloc_pages(gfp, order, preferred_nid, nodemask, &ac, &alloc_gfp, &alloc_flags)) return NULL;
__alloc_pages updates GFP flags to enforce what flags are allowed during a global context such as booting or suspend. This patch moves the enforcement from __alloc_pages to prepare_alloc_pages so the code can be shared between the single page allocator and a new bulk page allocator. When moving, it is obvious that __alloc_pages() and __alloc_pages use different names for the same variable. This is an unnecessary complication so rename gfp_mask to gfp in prepare_alloc_pages() so the name is consistent. No functional change. Signed-off-by: Mel Gorman <mgorman@techsingularity.net> --- mm/page_alloc.c | 25 +++++++++++++------------ 1 file changed, 13 insertions(+), 12 deletions(-)