| Message ID | 1598273705-69124-24-git-send-email-alex.shi@linux.alibaba.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | per memcg lru_lock | expand |
On Mon, 24 Aug 2020, Alex Shi wrote: > From: Hugh Dickins <hughd@google.com> > > Since we changed the pgdat->lru_lock to lruvec->lru_lock, it's time to > fix the incorrect comments in code. Also fixed some zone->lru_lock comment > error from ancient time. etc. > > Signed-off-by: Hugh Dickins <hughd@google.com> > Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com> I'm not the right person to be Acking this one; but when I scanned through, I did notice some wording had been added that I want to change. I should just send you a new version, but not tonight. > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Tejun Heo <tj@kernel.org> > Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> > Cc: Jann Horn <jannh@google.com> > Cc: Mel Gorman <mgorman@techsingularity.net> > Cc: Johannes Weiner <hannes@cmpxchg.org> > Cc: Matthew Wilcox <willy@infradead.org> > Cc: Hugh Dickins <hughd@google.com> > Cc: cgroups@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > Cc: linux-mm@kvack.org > --- > Documentation/admin-guide/cgroup-v1/memcg_test.rst | 15 +++------------ > Documentation/admin-guide/cgroup-v1/memory.rst | 21 +++++++++------------ > Documentation/trace/events-kmem.rst | 2 +- > Documentation/vm/unevictable-lru.rst | 22 ++++++++-------------- > include/linux/mm_types.h | 2 +- > include/linux/mmzone.h | 3 +-- > mm/filemap.c | 4 ++-- > mm/memcontrol.c | 2 +- > mm/rmap.c | 4 ++-- > mm/vmscan.c | 12 ++++++++---- > 10 files changed, 36 insertions(+), 51 deletions(-) > > diff --git a/Documentation/admin-guide/cgroup-v1/memcg_test.rst b/Documentation/admin-guide/cgroup-v1/memcg_test.rst > index 3f7115e07b5d..0b9f91589d3d 100644 > --- a/Documentation/admin-guide/cgroup-v1/memcg_test.rst > +++ b/Documentation/admin-guide/cgroup-v1/memcg_test.rst > @@ -133,18 +133,9 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y. > > 8. LRU > ====== > - Each memcg has its own private LRU. Now, its handling is under global > - VM's control (means that it's handled under global pgdat->lru_lock). > - Almost all routines around memcg's LRU is called by global LRU's > - list management functions under pgdat->lru_lock. > - > - A special function is mem_cgroup_isolate_pages(). This scans > - memcg's private LRU and call __isolate_lru_page() to extract a page > - from LRU. > - > - (By __isolate_lru_page(), the page is removed from both of global and > - private LRU.) > - > + Each memcg has its own vector of LRUs (inactive anon, active anon, > + inactive file, active file, unevictable) of pages from each node, > + each LRU handled under a single lru_lock for that memcg and node. > > 9. Typical Tests. > ================= > diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst > index 12757e63b26c..24450696579f 100644 > --- a/Documentation/admin-guide/cgroup-v1/memory.rst > +++ b/Documentation/admin-guide/cgroup-v1/memory.rst > @@ -285,20 +285,17 @@ When oom event notifier is registered, event will be delivered. > 2.6 Locking > ----------- > > - lock_page_cgroup()/unlock_page_cgroup() should not be called under > - the i_pages lock. > +Lock order is as follows: > > - Other lock order is following: > + Page lock (PG_locked bit of page->flags) > + mm->page_table_lock or split pte_lock > + lock_page_memcg (memcg->move_lock) > + mapping->i_pages lock > + lruvec->lru_lock. > > - PG_locked. > - mm->page_table_lock > - pgdat->lru_lock > - lock_page_cgroup. > - > - In many cases, just lock_page_cgroup() is called. > - > - per-zone-per-cgroup LRU (cgroup's private LRU) is just guarded by > - pgdat->lru_lock, it has no lock of its own. > +Per-node-per-memcgroup LRU (cgroup's private LRU) is guarded by > +lruvec->lru_lock; PG_lru bit of page->flags is cleared before > +isolating a page from its LRU under lruvec->lru_lock. > > 2.7 Kernel Memory Extension (CONFIG_MEMCG_KMEM) > ----------------------------------------------- > diff --git a/Documentation/trace/events-kmem.rst b/Documentation/trace/events-kmem.rst > index 555484110e36..68fa75247488 100644 > --- a/Documentation/trace/events-kmem.rst > +++ b/Documentation/trace/events-kmem.rst > @@ -69,7 +69,7 @@ When pages are freed in batch, the also mm_page_free_batched is triggered. > Broadly speaking, pages are taken off the LRU lock in bulk and > freed in batch with a page list. Significant amounts of activity here could > indicate that the system is under memory pressure and can also indicate > -contention on the zone->lru_lock. > +contention on the lruvec->lru_lock. > > 4. Per-CPU Allocator Activity > ============================= > diff --git a/Documentation/vm/unevictable-lru.rst b/Documentation/vm/unevictable-lru.rst > index 17d0861b0f1d..0e1490524f53 100644 > --- a/Documentation/vm/unevictable-lru.rst > +++ b/Documentation/vm/unevictable-lru.rst > @@ -33,7 +33,7 @@ reclaim in Linux. The problems have been observed at customer sites on large > memory x86_64 systems. > > To illustrate this with an example, a non-NUMA x86_64 platform with 128GB of > -main memory will have over 32 million 4k pages in a single zone. When a large > +main memory will have over 32 million 4k pages in a single node. When a large > fraction of these pages are not evictable for any reason [see below], vmscan > will spend a lot of time scanning the LRU lists looking for the small fraction > of pages that are evictable. This can result in a situation where all CPUs are > @@ -55,7 +55,7 @@ unevictable, either by definition or by circumstance, in the future. > The Unevictable Page List > ------------------------- > > -The Unevictable LRU infrastructure consists of an additional, per-zone, LRU list > +The Unevictable LRU infrastructure consists of an additional, per-node, LRU list > called the "unevictable" list and an associated page flag, PG_unevictable, to > indicate that the page is being managed on the unevictable list. > > @@ -84,15 +84,9 @@ The unevictable list does not differentiate between file-backed and anonymous, > swap-backed pages. This differentiation is only important while the pages are, > in fact, evictable. > > -The unevictable list benefits from the "arrayification" of the per-zone LRU > +The unevictable list benefits from the "arrayification" of the per-node LRU > lists and statistics originally proposed and posted by Christoph Lameter. > > -The unevictable list does not use the LRU pagevec mechanism. Rather, > -unevictable pages are placed directly on the page's zone's unevictable list > -under the zone lru_lock. This allows us to prevent the stranding of pages on > -the unevictable list when one task has the page isolated from the LRU and other > -tasks are changing the "evictability" state of the page. > - > > Memory Control Group Interaction > -------------------------------- > @@ -101,8 +95,8 @@ The unevictable LRU facility interacts with the memory control group [aka > memory controller; see Documentation/admin-guide/cgroup-v1/memory.rst] by extending the > lru_list enum. > > -The memory controller data structure automatically gets a per-zone unevictable > -list as a result of the "arrayification" of the per-zone LRU lists (one per > +The memory controller data structure automatically gets a per-node unevictable > +list as a result of the "arrayification" of the per-node LRU lists (one per > lru_list enum element). The memory controller tracks the movement of pages to > and from the unevictable list. > > @@ -196,7 +190,7 @@ for the sake of expediency, to leave a unevictable page on one of the regular > active/inactive LRU lists for vmscan to deal with. vmscan checks for such > pages in all of the shrink_{active|inactive|page}_list() functions and will > "cull" such pages that it encounters: that is, it diverts those pages to the > -unevictable list for the zone being scanned. > +unevictable list for the node being scanned. > > There may be situations where a page is mapped into a VM_LOCKED VMA, but the > page is not marked as PG_mlocked. Such pages will make it all the way to > @@ -328,7 +322,7 @@ If the page was NOT already mlocked, mlock_vma_page() attempts to isolate the > page from the LRU, as it is likely on the appropriate active or inactive list > at that time. If the isolate_lru_page() succeeds, mlock_vma_page() will put > back the page - by calling putback_lru_page() - which will notice that the page > -is now mlocked and divert the page to the zone's unevictable list. If > +is now mlocked and divert the page to the node's unevictable list. If > mlock_vma_page() is unable to isolate the page from the LRU, vmscan will handle > it later if and when it attempts to reclaim the page. > > @@ -603,7 +597,7 @@ Some examples of these unevictable pages on the LRU lists are: > unevictable list in mlock_vma_page(). > > shrink_inactive_list() also diverts any unevictable pages that it finds on the > -inactive lists to the appropriate zone's unevictable list. > +inactive lists to the appropriate node's unevictable list. > > shrink_inactive_list() should only see SHM_LOCK'd pages that became SHM_LOCK'd > after shrink_active_list() had moved them to the inactive list, or pages mapped > diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h > index 496c3ff97cce..c3f1e76720af 100644 > --- a/include/linux/mm_types.h > +++ b/include/linux/mm_types.h > @@ -78,7 +78,7 @@ struct page { > struct { /* Page cache and anonymous pages */ > /** > * @lru: Pageout list, eg. active_list protected by > - * pgdat->lru_lock. Sometimes used as a generic list > + * lruvec->lru_lock. Sometimes used as a generic list > * by the page owner. > */ > struct list_head lru; > diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h > index 27a1513a43fc..f0596e634863 100644 > --- a/include/linux/mmzone.h > +++ b/include/linux/mmzone.h > @@ -113,8 +113,7 @@ static inline bool free_area_empty(struct free_area *area, int migratetype) > struct pglist_data; > > /* > - * zone->lock and the zone lru_lock are two of the hottest locks in the kernel. > - * So add a wild amount of padding here to ensure that they fall into separate > + * Add a wild amount of padding here to ensure datas fall into separate > * cachelines. There are very few zone structures in the machine, so space > * consumption is not a concern here. > */ > diff --git a/mm/filemap.c b/mm/filemap.c > index 1aaea26556cc..6f8d58fb16db 100644 > --- a/mm/filemap.c > +++ b/mm/filemap.c > @@ -102,8 +102,8 @@ > * ->swap_lock (try_to_unmap_one) > * ->private_lock (try_to_unmap_one) > * ->i_pages lock (try_to_unmap_one) > - * ->pgdat->lru_lock (follow_page->mark_page_accessed) > - * ->pgdat->lru_lock (check_pte_range->isolate_lru_page) > + * ->lruvec->lru_lock (follow_page->mark_page_accessed) > + * ->lruvec->lru_lock (check_pte_range->isolate_lru_page) > * ->private_lock (page_remove_rmap->set_page_dirty) > * ->i_pages lock (page_remove_rmap->set_page_dirty) > * bdi.wb->list_lock (page_remove_rmap->set_page_dirty) > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 5b95529e64a4..454b3f205d1b 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -3279,7 +3279,7 @@ void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size) > #ifdef CONFIG_TRANSPARENT_HUGEPAGE > > /* > - * Because tail pages are not marked as "used", set it. We're under > + * Because tail pages are not marked as "used", set it. Don't need > * lruvec->lru_lock and migration entries setup in all page mappings. > */ > void mem_cgroup_split_huge_fixup(struct page *head) > diff --git a/mm/rmap.c b/mm/rmap.c > index 83cc459edc40..259c323e06ea 100644 > --- a/mm/rmap.c > +++ b/mm/rmap.c > @@ -28,12 +28,12 @@ > * hugetlb_fault_mutex (hugetlbfs specific page fault mutex) > * anon_vma->rwsem > * mm->page_table_lock or pte_lock > - * pgdat->lru_lock (in mark_page_accessed, isolate_lru_page) > * swap_lock (in swap_duplicate, swap_info_get) > * mmlist_lock (in mmput, drain_mmlist and others) > * mapping->private_lock (in __set_page_dirty_buffers) > - * mem_cgroup_{begin,end}_page_stat (memcg->move_lock) > + * lock_page_memcg move_lock (in __set_page_dirty_buffers) > * i_pages lock (widely used) > + * lruvec->lru_lock (in lock_page_lruvec_irq) > * inode->i_lock (in set_page_dirty's __mark_inode_dirty) > * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty) > * sb_lock (within inode_lock in fs/fs-writeback.c) > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 04ef94190530..601fbcb994fb 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1614,14 +1614,16 @@ static __always_inline void update_lru_sizes(struct lruvec *lruvec, > } > > /** > - * pgdat->lru_lock is heavily contended. Some of the functions that > + * Isolating page from the lruvec to fill in @dst list by nr_to_scan times. > + * > + * lruvec->lru_lock is heavily contended. Some of the functions that > * shrink the lists perform better by taking out a batch of pages > * and working on them outside the LRU lock. > * > * For pagecache intensive workloads, this function is the hottest > * spot in the kernel (apart from copy_*_user functions). > * > - * Appropriate locks must be held before calling this function. > + * Lru_lock must be held before calling this function. > * > * @nr_to_scan: The number of eligible pages to look through on the list. > * @lruvec: The LRU vector to pull pages from. > @@ -1820,14 +1822,16 @@ static int too_many_isolated(struct pglist_data *pgdat, int file, > > /* > * This moves pages from @list to corresponding LRU list. > + * The pages from @list is out of any lruvec, and in the end list reuses as > + * pages_to_free list. > * > * We move them the other way if the page is referenced by one or more > * processes, from rmap. > * > * If the pages are mostly unmapped, the processing is fast and it is > - * appropriate to hold zone_lru_lock across the whole operation. But if > + * appropriate to hold lru_lock across the whole operation. But if > * the pages are mapped, the processing is slow (page_referenced()) so we > - * should drop zone_lru_lock around each page. It's impossible to balance > + * should drop lru_lock around each page. It's impossible to balance > * this, so instead we remove the pages from the LRU while processing them. > * It is safe to rely on PG_active against the non-LRU pages in here because > * nobody will play with that bit on a non-LRU page. > -- > 1.8.3.1 > >
diff --git a/Documentation/admin-guide/cgroup-v1/memcg_test.rst b/Documentation/admin-guide/cgroup-v1/memcg_test.rst index 3f7115e07b5d..0b9f91589d3d 100644 --- a/Documentation/admin-guide/cgroup-v1/memcg_test.rst +++ b/Documentation/admin-guide/cgroup-v1/memcg_test.rst @@ -133,18 +133,9 @@ Under below explanation, we assume CONFIG_MEM_RES_CTRL_SWAP=y. 8. LRU ====== - Each memcg has its own private LRU. Now, its handling is under global - VM's control (means that it's handled under global pgdat->lru_lock). - Almost all routines around memcg's LRU is called by global LRU's - list management functions under pgdat->lru_lock. - - A special function is mem_cgroup_isolate_pages(). This scans - memcg's private LRU and call __isolate_lru_page() to extract a page - from LRU. - - (By __isolate_lru_page(), the page is removed from both of global and - private LRU.) - + Each memcg has its own vector of LRUs (inactive anon, active anon, + inactive file, active file, unevictable) of pages from each node, + each LRU handled under a single lru_lock for that memcg and node. 9. Typical Tests. ================= diff --git a/Documentation/admin-guide/cgroup-v1/memory.rst b/Documentation/admin-guide/cgroup-v1/memory.rst index 12757e63b26c..24450696579f 100644 --- a/Documentation/admin-guide/cgroup-v1/memory.rst +++ b/Documentation/admin-guide/cgroup-v1/memory.rst @@ -285,20 +285,17 @@ When oom event notifier is registered, event will be delivered. 2.6 Locking ----------- - lock_page_cgroup()/unlock_page_cgroup() should not be called under - the i_pages lock. +Lock order is as follows: - Other lock order is following: + Page lock (PG_locked bit of page->flags) + mm->page_table_lock or split pte_lock + lock_page_memcg (memcg->move_lock) + mapping->i_pages lock + lruvec->lru_lock. - PG_locked. - mm->page_table_lock - pgdat->lru_lock - lock_page_cgroup. - - In many cases, just lock_page_cgroup() is called. - - per-zone-per-cgroup LRU (cgroup's private LRU) is just guarded by - pgdat->lru_lock, it has no lock of its own. +Per-node-per-memcgroup LRU (cgroup's private LRU) is guarded by +lruvec->lru_lock; PG_lru bit of page->flags is cleared before +isolating a page from its LRU under lruvec->lru_lock. 2.7 Kernel Memory Extension (CONFIG_MEMCG_KMEM) ----------------------------------------------- diff --git a/Documentation/trace/events-kmem.rst b/Documentation/trace/events-kmem.rst index 555484110e36..68fa75247488 100644 --- a/Documentation/trace/events-kmem.rst +++ b/Documentation/trace/events-kmem.rst @@ -69,7 +69,7 @@ When pages are freed in batch, the also mm_page_free_batched is triggered. Broadly speaking, pages are taken off the LRU lock in bulk and freed in batch with a page list. Significant amounts of activity here could indicate that the system is under memory pressure and can also indicate -contention on the zone->lru_lock. +contention on the lruvec->lru_lock. 4. Per-CPU Allocator Activity ============================= diff --git a/Documentation/vm/unevictable-lru.rst b/Documentation/vm/unevictable-lru.rst index 17d0861b0f1d..0e1490524f53 100644 --- a/Documentation/vm/unevictable-lru.rst +++ b/Documentation/vm/unevictable-lru.rst @@ -33,7 +33,7 @@ reclaim in Linux. The problems have been observed at customer sites on large memory x86_64 systems. To illustrate this with an example, a non-NUMA x86_64 platform with 128GB of -main memory will have over 32 million 4k pages in a single zone. When a large +main memory will have over 32 million 4k pages in a single node. When a large fraction of these pages are not evictable for any reason [see below], vmscan will spend a lot of time scanning the LRU lists looking for the small fraction of pages that are evictable. This can result in a situation where all CPUs are @@ -55,7 +55,7 @@ unevictable, either by definition or by circumstance, in the future. The Unevictable Page List ------------------------- -The Unevictable LRU infrastructure consists of an additional, per-zone, LRU list +The Unevictable LRU infrastructure consists of an additional, per-node, LRU list called the "unevictable" list and an associated page flag, PG_unevictable, to indicate that the page is being managed on the unevictable list. @@ -84,15 +84,9 @@ The unevictable list does not differentiate between file-backed and anonymous, swap-backed pages. This differentiation is only important while the pages are, in fact, evictable. -The unevictable list benefits from the "arrayification" of the per-zone LRU +The unevictable list benefits from the "arrayification" of the per-node LRU lists and statistics originally proposed and posted by Christoph Lameter. -The unevictable list does not use the LRU pagevec mechanism. Rather, -unevictable pages are placed directly on the page's zone's unevictable list -under the zone lru_lock. This allows us to prevent the stranding of pages on -the unevictable list when one task has the page isolated from the LRU and other -tasks are changing the "evictability" state of the page. - Memory Control Group Interaction -------------------------------- @@ -101,8 +95,8 @@ The unevictable LRU facility interacts with the memory control group [aka memory controller; see Documentation/admin-guide/cgroup-v1/memory.rst] by extending the lru_list enum. -The memory controller data structure automatically gets a per-zone unevictable -list as a result of the "arrayification" of the per-zone LRU lists (one per +The memory controller data structure automatically gets a per-node unevictable +list as a result of the "arrayification" of the per-node LRU lists (one per lru_list enum element). The memory controller tracks the movement of pages to and from the unevictable list. @@ -196,7 +190,7 @@ for the sake of expediency, to leave a unevictable page on one of the regular active/inactive LRU lists for vmscan to deal with. vmscan checks for such pages in all of the shrink_{active|inactive|page}_list() functions and will "cull" such pages that it encounters: that is, it diverts those pages to the -unevictable list for the zone being scanned. +unevictable list for the node being scanned. There may be situations where a page is mapped into a VM_LOCKED VMA, but the page is not marked as PG_mlocked. Such pages will make it all the way to @@ -328,7 +322,7 @@ If the page was NOT already mlocked, mlock_vma_page() attempts to isolate the page from the LRU, as it is likely on the appropriate active or inactive list at that time. If the isolate_lru_page() succeeds, mlock_vma_page() will put back the page - by calling putback_lru_page() - which will notice that the page -is now mlocked and divert the page to the zone's unevictable list. If +is now mlocked and divert the page to the node's unevictable list. If mlock_vma_page() is unable to isolate the page from the LRU, vmscan will handle it later if and when it attempts to reclaim the page. @@ -603,7 +597,7 @@ Some examples of these unevictable pages on the LRU lists are: unevictable list in mlock_vma_page(). shrink_inactive_list() also diverts any unevictable pages that it finds on the -inactive lists to the appropriate zone's unevictable list. +inactive lists to the appropriate node's unevictable list. shrink_inactive_list() should only see SHM_LOCK'd pages that became SHM_LOCK'd after shrink_active_list() had moved them to the inactive list, or pages mapped diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 496c3ff97cce..c3f1e76720af 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -78,7 +78,7 @@ struct page { struct { /* Page cache and anonymous pages */ /** * @lru: Pageout list, eg. active_list protected by - * pgdat->lru_lock. Sometimes used as a generic list + * lruvec->lru_lock. Sometimes used as a generic list * by the page owner. */ struct list_head lru; diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h index 27a1513a43fc..f0596e634863 100644 --- a/include/linux/mmzone.h +++ b/include/linux/mmzone.h @@ -113,8 +113,7 @@ static inline bool free_area_empty(struct free_area *area, int migratetype) struct pglist_data; /* - * zone->lock and the zone lru_lock are two of the hottest locks in the kernel. - * So add a wild amount of padding here to ensure that they fall into separate + * Add a wild amount of padding here to ensure datas fall into separate * cachelines. There are very few zone structures in the machine, so space * consumption is not a concern here. */ diff --git a/mm/filemap.c b/mm/filemap.c index 1aaea26556cc..6f8d58fb16db 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -102,8 +102,8 @@ * ->swap_lock (try_to_unmap_one) * ->private_lock (try_to_unmap_one) * ->i_pages lock (try_to_unmap_one) - * ->pgdat->lru_lock (follow_page->mark_page_accessed) - * ->pgdat->lru_lock (check_pte_range->isolate_lru_page) + * ->lruvec->lru_lock (follow_page->mark_page_accessed) + * ->lruvec->lru_lock (check_pte_range->isolate_lru_page) * ->private_lock (page_remove_rmap->set_page_dirty) * ->i_pages lock (page_remove_rmap->set_page_dirty) * bdi.wb->list_lock (page_remove_rmap->set_page_dirty) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 5b95529e64a4..454b3f205d1b 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3279,7 +3279,7 @@ void obj_cgroup_uncharge(struct obj_cgroup *objcg, size_t size) #ifdef CONFIG_TRANSPARENT_HUGEPAGE /* - * Because tail pages are not marked as "used", set it. We're under + * Because tail pages are not marked as "used", set it. Don't need * lruvec->lru_lock and migration entries setup in all page mappings. */ void mem_cgroup_split_huge_fixup(struct page *head) diff --git a/mm/rmap.c b/mm/rmap.c index 83cc459edc40..259c323e06ea 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -28,12 +28,12 @@ * hugetlb_fault_mutex (hugetlbfs specific page fault mutex) * anon_vma->rwsem * mm->page_table_lock or pte_lock - * pgdat->lru_lock (in mark_page_accessed, isolate_lru_page) * swap_lock (in swap_duplicate, swap_info_get) * mmlist_lock (in mmput, drain_mmlist and others) * mapping->private_lock (in __set_page_dirty_buffers) - * mem_cgroup_{begin,end}_page_stat (memcg->move_lock) + * lock_page_memcg move_lock (in __set_page_dirty_buffers) * i_pages lock (widely used) + * lruvec->lru_lock (in lock_page_lruvec_irq) * inode->i_lock (in set_page_dirty's __mark_inode_dirty) * bdi.wb->list_lock (in set_page_dirty's __mark_inode_dirty) * sb_lock (within inode_lock in fs/fs-writeback.c) diff --git a/mm/vmscan.c b/mm/vmscan.c index 04ef94190530..601fbcb994fb 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -1614,14 +1614,16 @@ static __always_inline void update_lru_sizes(struct lruvec *lruvec, } /** - * pgdat->lru_lock is heavily contended. Some of the functions that + * Isolating page from the lruvec to fill in @dst list by nr_to_scan times. + * + * lruvec->lru_lock is heavily contended. Some of the functions that * shrink the lists perform better by taking out a batch of pages * and working on them outside the LRU lock. * * For pagecache intensive workloads, this function is the hottest * spot in the kernel (apart from copy_*_user functions). * - * Appropriate locks must be held before calling this function. + * Lru_lock must be held before calling this function. * * @nr_to_scan: The number of eligible pages to look through on the list. * @lruvec: The LRU vector to pull pages from. @@ -1820,14 +1822,16 @@ static int too_many_isolated(struct pglist_data *pgdat, int file, /* * This moves pages from @list to corresponding LRU list. + * The pages from @list is out of any lruvec, and in the end list reuses as + * pages_to_free list. * * We move them the other way if the page is referenced by one or more * processes, from rmap. * * If the pages are mostly unmapped, the processing is fast and it is - * appropriate to hold zone_lru_lock across the whole operation. But if + * appropriate to hold lru_lock across the whole operation. But if * the pages are mapped, the processing is slow (page_referenced()) so we - * should drop zone_lru_lock around each page. It's impossible to balance + * should drop lru_lock around each page. It's impossible to balance * this, so instead we remove the pages from the LRU while processing them. * It is safe to rely on PG_active against the non-LRU pages in here because * nobody will play with that bit on a non-LRU page.