search for: page_lock

...we use it only as a heuristic. But I guess it would require at least RCU-level protection of the page->mapping->a_op->isolate_page chain. > For avoiding that, we need another function to peek which just checks > PG_movable bit instead of all things. > > > /* > * If @page_locked is false, we cannot guarantee page->mapping's stability > * so just the function checks with PG_movable which could be false positive > * so caller should check it again under PG_lock to check a_ops->isolate_page. > */ > static inline int PageMovable(struct page *page,...

...we use it only as a heuristic. But I guess it would require at least RCU-level protection of the page->mapping->a_op->isolate_page chain. > For avoiding that, we need another function to peek which just checks > PG_movable bit instead of all things. > > > /* > * If @page_locked is false, we cannot guarantee page->mapping's stability > * so just the function checks with PG_movable which could be false positive > * so caller should check it again under PG_lock to check a_ops->isolate_page. > */ > static inline int PageMovable(struct page *page,...

On 04/04/2016 04:25 AM, Minchan Kim wrote: >> >> Ah, I see, so it's designed with page lock to handle the concurrent isolations etc. >> >> In http://marc.info/?l=linux-mm&m=143816716511904&w=2 Mel has warned >> about doing this in general under page_lock and suggested that each >> user handles concurrent calls to isolate_page() internally. Might be >> more generic that way, even if all current implementers will >> actually use the page lock. > > We need PG_lock for two reasons. > > Firstly, it guarantees page's fla...

On 04/04/2016 04:25 AM, Minchan Kim wrote: >> >> Ah, I see, so it's designed with page lock to handle the concurrent isolations etc. >> >> In http://marc.info/?l=linux-mm&m=143816716511904&w=2 Mel has warned >> about doing this in general under page_lock and suggested that each >> user handles concurrent calls to isolate_page() internally. Might be >> more generic that way, even if all current implementers will >> actually use the page lock. > > We need PG_lock for two reasons. > > Firstly, it guarantees page's fla...

...ldpage, enum migrate_mode); After isolation, VM calls migratepage of driver with isolated page. The function of migratepage is to move content of the old page to new page and set up fields of struct page newpage. Keep in mind that you should clear PG_movable of oldpage via __ClearPageMovable under page_lock if you migrated the oldpage successfully and returns 0. If driver cannot migrate the page at the moment, driver can return -EAGAIN. On -EAGAIN, VM will retry page migration in a short time because VM interprets -EAGAIN as "temporal migration failure". On returning any error except -EAGAIN...

...ldpage, enum migrate_mode); After isolation, VM calls migratepage of driver with isolated page. The function of migratepage is to move content of the old page to new page and set up fields of struct page newpage. Keep in mind that you should clear PG_movable of oldpage via __ClearPageMovable under page_lock if you migrated the oldpage successfully and returns 0. If driver cannot migrate the page at the moment, driver can return -EAGAIN. On -EAGAIN, VM will retry page migration in a short time because VM interprets -EAGAIN as "temporal migration failure". On returning any error except -EAGAIN...

...t;After isolation, VM calls migratepage of driver with isolated page. > >The function of migratepage is to move content of the old page to new page > >and set up fields of struct page newpage. Keep in mind that you should > >clear PG_movable of oldpage via __ClearPageMovable under page_lock if you > >migrated the oldpage successfully and returns 0. > > This "clear PG_movable" is one of the reasons I was confused about > what __ClearPageMovable() really does. There's no actual > "PG_movable" page flag and the function doesn't clear even th...

...t;After isolation, VM calls migratepage of driver with isolated page. > >The function of migratepage is to move content of the old page to new page > >and set up fields of struct page newpage. Keep in mind that you should > >clear PG_movable of oldpage via __ClearPageMovable under page_lock if you > >migrated the oldpage successfully and returns 0. > > This "clear PG_movable" is one of the reasons I was confused about > what __ClearPageMovable() really does. There's no actual > "PG_movable" page flag and the function doesn't clear even th...

...ldpage, enum migrate_mode); After isolation, VM calls migratepage of driver with isolated page. The function of migratepage is to move content of the old page to new page and set up fields of struct page newpage. Keep in mind that you should clear PG_movable of oldpage via __ClearPageMovable under page_lock if you migrated the oldpage successfully and returns MIGRATEPAGE_SUCCESS. If driver cannot migrate the page at the moment, driver can return -EAGAIN. On -EAGAIN, VM will retry page migration in a short time because VM interprets -EAGAIN as "temporal migration failure". On returning any er...

...ct lguest_guest_info *linfo; + int err; + u64 args[4]; + int i; + + if (file->private_data) + return -EBUSY; + + if (copy_from_user(args, input, sizeof(args)) != 0) + return -EFAULT; + + linfo = kzalloc(sizeof(*linfo), GFP_KERNEL); + if (!linfo) + return -ENOMEM; + + mutex_init(&linfo->page_lock); + + /* FIXME: protect the guest_id counter */ + linfo->guest_id = ++next_guest_id; + + linfo->pfn_limit = args[0]; + linfo->page_offset = args[3]; + linfo->start_kernel_map = args[3]; + + mutex_init(&linfo->page_lock); + INIT_LIST_HEAD(&linfo->pgd_list); + + for (i=0; i...

...ct lguest_guest_info *linfo; + int err; + u64 args[4]; + int i; + + if (file->private_data) + return -EBUSY; + + if (copy_from_user(args, input, sizeof(args)) != 0) + return -EFAULT; + + linfo = kzalloc(sizeof(*linfo), GFP_KERNEL); + if (!linfo) + return -ENOMEM; + + mutex_init(&linfo->page_lock); + + /* FIXME: protect the guest_id counter */ + linfo->guest_id = ++next_guest_id; + + linfo->pfn_limit = args[0]; + linfo->page_offset = args[3]; + linfo->start_kernel_map = args[3]; + + mutex_init(&linfo->page_lock); + INIT_LIST_HEAD(&linfo->pgd_list); + + for (i=0; i...

...ldpage, enum migrate_mode); After isolation, VM calls migratepage of driver with isolated page. The function of migratepage is to move content of the old page to new page and set up fields of struct page newpage. Keep in mind that you should clear PG_movable of oldpage via __ClearPageMovable under page_lock if you migrated the oldpage successfully and returns 0. If driver cannot migrate the page at the moment, driver can return -EAGAIN. On -EAGAIN, VM will retry page migration in a short time because VM interprets -EAGAIN as "temporal migration failure". On returning any error except -EAGAIN...

...e); > > After isolation, VM calls migratepage of driver with isolated page. > The function of migratepage is to move content of the old page to new page > and set up fields of struct page newpage. Keep in mind that you should > clear PG_movable of oldpage via __ClearPageMovable under page_lock if you > migrated the oldpage successfully and returns 0. > If driver cannot migrate the page at the moment, driver can return -EAGAIN. > On -EAGAIN, VM will retry page migration in a short time because VM interprets > -EAGAIN as "temporal migration failure". On returning any...

...e); > > After isolation, VM calls migratepage of driver with isolated page. > The function of migratepage is to move content of the old page to new page > and set up fields of struct page newpage. Keep in mind that you should > clear PG_movable of oldpage via __ClearPageMovable under page_lock if you > migrated the oldpage successfully and returns 0. > If driver cannot migrate the page at the moment, driver can return -EAGAIN. > On -EAGAIN, VM will retry page migration in a short time because VM interprets > -EAGAIN as "temporal migration failure". On returning any...

...fix - Sergey * add additional Reviewed-by for zsmalloc - Sergey * From v4 * rebase on mmotm-2016-05-05-17-19 * fix huge object migration - Chulmin * !CONFIG_COMPACTION support for zsmalloc * From v3 * rebase on mmotm-2016-04-06-20-40 * fix swap_info deadlock - Chulmin * race without page_lock - Vlastimil * no use page._mapcount for potential user-mapped page driver - Vlastimil * fix and enhance doc/description - Vlastimil * use page->mapping lower bits to represent PG_movable * make driver side's rule simple. * From v2 * rebase on mmotm-2016-03-29-15-54-16 * check Pa...

...fix - Sergey * add additional Reviewed-by for zsmalloc - Sergey * From v4 * rebase on mmotm-2016-05-05-17-19 * fix huge object migration - Chulmin * !CONFIG_COMPACTION support for zsmalloc * From v3 * rebase on mmotm-2016-04-06-20-40 * fix swap_info deadlock - Chulmin * race without page_lock - Vlastimil * no use page._mapcount for potential user-mapped page driver - Vlastimil * fix and enhance doc/description - Vlastimil * use page->mapping lower bits to represent PG_movable * make driver side's rule simple. * From v2 * rebase on mmotm-2016-03-29-15-54-16 * check Pa...

...; After isolation, VM calls migratepage of driver with isolated page. The function of migratepage is to move content of the old page to new page and set up fields of struct page newpage. Keep in mind that you should indicate to the VM the oldpage is no longer movable via __ClearPageMovable() under page_lock if you migrated the oldpage successfully and returns 0. If driver cannot migrate the page at the moment, driver can return -EAGAIN. On -EAGAIN, VM will retry page migration in a short time because VM interprets -EAGAIN as "temporal migration failure". On returning any error except -EAGAIN...

...t;After isolation, VM calls migratepage of driver with isolated page. > >The function of migratepage is to move content of the old page to new page > >and set up fields of struct page newpage. Keep in mind that you should > >clear PG_movable of oldpage via __ClearPageMovable under page_lock if you > >migrated the oldpage successfully and returns 0. > >If driver cannot migrate the page at the moment, driver can return -EAGAIN. > >On -EAGAIN, VM will retry page migration in a short time because VM interprets > >-EAGAIN as "temporal migration failure". O...

Might have been better as a separate migration patch and then a compaction patch. It's prefixed mm/compaction, but most changed are in mm/migrate.c On 03/30/2016 09:12 AM, Minchan Kim wrote: > We have allowed migration for only LRU pages until now and it was > enough to make high-order pages. But recently, embedded system(e.g., > webOS, android) uses lots of non-movable pages(e.g.,

Might have been better as a separate migration patch and then a compaction patch. It's prefixed mm/compaction, but most changed are in mm/migrate.c On 03/30/2016 09:12 AM, Minchan Kim wrote: > We have allowed migration for only LRU pages until now and it was > enough to make high-order pages. But recently, embedded system(e.g., > webOS, android) uses lots of non-movable pages(e.g.,