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* [PATCH] mm: tracking shared dirty pagesPeter Zijlstra2006-09-261-0/+65
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Tracking of dirty pages in shared writeable mmap()s. The idea is simple: write protect clean shared writeable pages, catch the write-fault, make writeable and set dirty. On page write-back clean all the PTE dirty bits and write protect them once again. The implementation is a tad harder, mainly because the default backing_dev_info capabilities were too loosely maintained. Hence it is not enough to test the backing_dev_info for cap_account_dirty. The current heuristic is as follows, a VMA is eligible when: - its shared writeable (vm_flags & (VM_WRITE|VM_SHARED)) == (VM_WRITE|VM_SHARED) - it is not a 'special' mapping (vm_flags & (VM_PFNMAP|VM_INSERTPAGE)) == 0 - the backing_dev_info is cap_account_dirty mapping_cap_account_dirty(vma->vm_file->f_mapping) - f_op->mmap() didn't change the default page protection Page from remap_pfn_range() are explicitly excluded because their COW semantics are already horrid enough (see vm_normal_page() in do_wp_page()) and because they don't have a backing store anyway. mprotect() is taught about the new behaviour as well. However it overrides the last condition. Cleaning the pages on write-back is done with page_mkclean() a new rmap call. It can be called on any page, but is currently only implemented for mapped pages, if the page is found the be of a VMA that accounts dirty pages it will also wrprotect the PTE. Finally, in fs/buffers.c:try_to_free_buffers(); remove clear_page_dirty() from under ->private_lock. This seems to be safe, since ->private_lock is used to serialize access to the buffers, not the page itself. This is needed because clear_page_dirty() will call into page_mkclean() and would thereby violate locking order. [dhowells@redhat.com: Provide a page_mkclean() implementation for NOMMU] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] zoned vm counters: split NR_ANON_PAGES off from NR_FILE_MAPPEDChristoph Lameter2006-06-301-2/+3
| | | | | | | | | | | | | | | | | | | | | | | | | The current NR_FILE_MAPPED is used by zone reclaim and the dirty load calculation as the number of mapped pagecache pages. However, that is not true. NR_FILE_MAPPED includes the mapped anonymous pages. This patch separates those and therefore allows an accurate tracking of the anonymous pages per zone. It then becomes possible to determine the number of unmapped pages per zone and we can avoid scanning for unmapped pages if there are none. Also it may now be possible to determine the mapped/unmapped ratio in get_dirty_limit. Isnt the number of anonymous pages irrelevant in that calculation? Note that this will change the meaning of the number of mapped pages reported in /proc/vmstat /proc/meminfo and in the per node statistics. This may affect user space tools that monitor these counters! NR_FILE_MAPPED works like NR_FILE_DIRTY. It is only valid for pagecache pages. Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] zoned vm counters: convert nr_mapped to per zone counterChristoph Lameter2006-06-301-3/+3
| | | | | | | | | | | | | | | | | | | | nr_mapped is important because it allows a determination of how many pages of a zone are not mapped, which would allow a more efficient means of determining when we need to reclaim memory in a zone. We take the nr_mapped field out of the page state structure and define a new per zone counter named NR_FILE_MAPPED (the anonymous pages will be split off from NR_MAPPED in the next patch). We replace the use of nr_mapped in various kernel locations. This avoids the looping over all processors in try_to_free_pages(), writeback, reclaim (swap + zone reclaim). [akpm@osdl.org: bugfix] Signed-off-by: Christoph Lameter <clameter@sgi.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Allow migration of mlocked pagesChristoph Lameter2006-06-251-5/+4Star
| | | | | | | | | | | | | Hugh clarified the role of VM_LOCKED. So we can now implement page migration for mlocked pages. Allow the migration of mlocked pages. This means that try_to_unmap must unmap mlocked pages in the migration case. Signed-off-by: Christoph Lameter <clameter@sgi.com> Acked-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] More page migration: use migration entries for file pagesChristoph Lameter2006-06-231-0/+11
| | | | | | | | | | | | | | | | | This implements the use of migration entries to preserve ptes of file backed pages during migration. Processes can therefore be migrated back and forth without loosing their connection to pagecache pages. Note that we implement the migration entries only for linear mappings. Nonlinear mappings still require the unmapping of the ptes for migration. And another writepage() ugliness shows up. writepage() can drop the page lock. Therefore we have to remove migration ptes before calling writepages() in order to avoid having migration entries point to unlocked pages. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] More page migration: do not inc/dec rss countersChristoph Lameter2006-06-231-1/+1
| | | | | | | | | | | If we install a migration entry then the rss not really decreases since the page is just moved somewhere else. We can save ourselves the work of decrementing and later incrementing which will just eventually cause cacheline bouncing. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Swapless page migration: rip out swap based logicChristoph Lameter2006-06-231-38/+0Star
| | | | | | | | | | | | | | | Rip the page migration logic out. Remove all code that has to do with swapping during page migration. This also guts the ability to migrate pages to swap. No one used that so lets let it go for good. Page migration should be a bit broken after this patch. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Swapless page migration: add R/W migration entriesChristoph Lameter2006-06-231-14/+24
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Implement read/write migration ptes We take the upper two swapfiles for the two types of migration ptes and define a series of macros in swapops.h. The VM is modified to handle the migration entries. migration entries can only be encountered when the page they are pointing to is locked. This limits the number of places one has to fix. We also check in copy_pte_range and in mprotect_pte_range() for migration ptes. We check for migration ptes in do_swap_cache and call a function that will then wait on the page lock. This allows us to effectively stop all accesses to apge. Migration entries are created by try_to_unmap if called for migration and removed by local functions in migrate.c From: Hugh Dickins <hugh@veritas.com> Several times while testing swapless page migration (I've no NUMA, just hacking it up to migrate recklessly while running load), I've hit the BUG_ON(!PageLocked(p)) in migration_entry_to_page. This comes from an orphaned migration entry, unrelated to the current correctly locked migration, but hit by remove_anon_migration_ptes as it checks an address in each vma of the anon_vma list. Such an orphan may be left behind if an earlier migration raced with fork: copy_one_pte can duplicate a migration entry from parent to child, after remove_anon_migration_ptes has checked the child vma, but before it has removed it from the parent vma. (If the process were later to fault on this orphaned entry, it would hit the same BUG from migration_entry_wait.) This could be fixed by locking anon_vma in copy_one_pte, but we'd rather not. There's no such problem with file pages, because vma_prio_tree_add adds child vma after parent vma, and the page table locking at each end is enough to serialize. Follow that example with anon_vma: add new vmas to the tail instead of the head. (There's no corresponding problem when inserting migration entries, because a missed pte will leave the page count and mapcount high, which is allowed for. And there's no corresponding problem when migrating via swap, because a leftover swap entry will be correctly faulted. But the swapless method has no refcounting of its entries.) From: Ingo Molnar <mingo@elte.hu> pte_unmap_unlock() takes the pte pointer as an argument. From: Hugh Dickins <hugh@veritas.com> Several times while testing swapless page migration, gcc has tried to exec a pointer instead of a string: smells like COW mappings are not being properly write-protected on fork. The protection in copy_one_pte looks very convincing, until at last you realize that the second arg to make_migration_entry is a boolean "write", and SWP_MIGRATION_READ is 30. Anyway, it's better done like in change_pte_range, using is_write_migration_entry and make_migration_entry_read. From: Hugh Dickins <hugh@veritas.com> Remove unnecessary obfuscation from sys_swapon's range check on swap type, which blew up causing memory corruption once swapless migration made MAX_SWAPFILES no longer 2 ^ MAX_SWAPFILES_SHIFT. Signed-off-by: Hugh Dickins <hugh@veritas.com> Acked-by: Martin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> From: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] page migration cleanup: rename "ignrefs" to "migration"Christoph Lameter2006-06-231-9/+9
| | | | | | | | migrate is a better name since it is only used by page migration. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: more CONFIG_DEBUG_VMNick Piggin2006-03-221-5/+4Star
| | | | | | | | Put a few more checks under CONFIG_DEBUG_VM Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: kill kmem_cache_t usagePekka Enberg2006-03-221-2/+3
| | | | | | | | We have struct kmem_cache now so use it instead of the old typedef. Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] page_add_file_rmap(): remove BUG_ON()sHugh Dickins2006-03-101-3/+0Star
| | | | | | | | | | | | | | | | Remove two early-development BUG_ONs from page_add_file_rmap. The pfn_valid test (originally useful for checking that nobody passed an artificial struct page) comes too late, since we already have the struct page. The PageAnon test (useful when anon was first distinguished from file rmap) prevents ->nopage implementations from reusing ->mapping, which would otherwise be available. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] remove_from_swap: fix lockingChristoph Lameter2006-03-011-5/+13
| | | | | | | | | | | | | | | remove_from_swap() currently attempts to use page_lock_anon_vma to obtain an anon_vma lock. That is not working since the page may have been remapped via swap ptes in order to move the page. However, do_migrate_pages() obtain the mmap_sem lock and therefore there is a guarantee that the anonymous vma will not vanish from under us. There is therefore no need to use page_lock_anon_vma. Signed-off-by: Christoph Lameter <clameter@sgi.com> Acked-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Direct Migration V9: Avoid writeback / page_migrate() methodChristoph Lameter2006-02-011-0/+1
| | | | | | | | | | | | | | | | | | | Migrate a page with buffers without requiring writeback This introduces a new address space operation migratepage() that may be used by a filesystem to implement its own version of page migration. A version is provided that migrates buffers attached to pages. Some filesystems (ext2, ext3, xfs) are modified to utilize this feature. The swapper address space operation are modified so that a regular migrate_page() will occur for anonymous pages without writeback (migrate_pages forces every anonymous page to have a swap entry). Signed-off-by: Mike Kravetz <kravetz@us.ibm.com> Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Direct Migration V9: remove_from_swap() to remove swap ptesChristoph Lameter2006-02-011-0/+29
| | | | | | | | | | | | | Add remove_from_swap remove_from_swap() allows the restoration of the pte entries that existed before page migration occurred for anonymous pages by walking the reverse maps. This reduces swap use and establishes regular pte's without the need for page faults. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Direct Migration V9: migrate_pages() extensionChristoph Lameter2006-02-011-9/+12
| | | | | | | | | | | | | | | | | | | | | | | | | Add direct migration support with fall back to swap. Direct migration support on top of the swap based page migration facility. This allows the direct migration of anonymous pages and the migration of file backed pages by dropping the associated buffers (requires writeout). Fall back to swap out if necessary. The patch is based on lots of patches from the hotplug project but the code was restructured, documented and simplified as much as possible. Note that an additional patch that defines the migrate_page() method for filesystems is necessary in order to avoid writeback for anonymous and file backed pages. Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Signed-off-by: Mike Kravetz <kravetz@us.ibm.com> Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: migration page refcounting fixNick Piggin2006-01-191-1/+1
| | | | | | | | | | | | | | | | | Migration code currently does not take a reference to target page properly, so between unlocking the pte and trying to take a new reference to the page with isolate_lru_page, anything could happen to it. Fix this by holding the pte lock until we get a chance to elevate the refcount. Other small cleanups while we're here. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mutex subsystem, semaphore to mutex: VFS, ->i_semJes Sorensen2006-01-101-4/+4
| | | | | | | | | | | | | This patch converts the inode semaphore to a mutex. I have tested it on XFS and compiled as much as one can consider on an ia64. Anyway your luck with it might be different. Modified-by: Ingo Molnar <mingo@elte.hu> (finished the conversion) Signed-off-by: Jes Sorensen <jes@sgi.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
* [PATCH] rmap: additional diagnostics in page_remove_rmap()Dave Jones2006-01-091-0/+7
| | | | | | | | | | We seem to be hitting this assertion failure too often for it to be hardware bugs. Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: page_state optNick Piggin2006-01-061-3/+7
| | | | | | | | | | | | | | Optimise page_state manipulations by introducing interrupt unsafe accessors to page_state fields. Callers must provide their own locking (either disable interrupts or not update from interrupt context). Switch over the hot callsites that can easily be moved under interrupts off sections. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: rmap optimisationNick Piggin2006-01-061-11/+38
| | | | | | | | | | Optimise rmap functions by minimising atomic operations when we know there will be no concurrent modifications. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Fix missing pfn variables caused by vm changesBen Collins2005-11-291-1/+1
| | | | | | | | | I image this showed up because of "unused var..." when the changes occured, because flush_cache_page() is a noop in most places. This showed up for me on parisc however, where flush_cache_page() is a real function. Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] temporarily disable swap token on memory pressureRik van Riel2005-11-281-16/+10Star
| | | | | | | | | | | | | | | | | | | | Some users (hi Zwane) have seen a problem when running a workload that eats nearly all of physical memory - th system does an OOM kill, even when there is still a lot of swap free. The problem appears to be a very big task that is holding the swap token, and the VM has a very hard time finding any other page in the system that is swappable. Instead of ignoring the swap token when sc->priority reaches 0, we could simply take the swap token away from the memory hog and make sure we don't give it back to the memory hog for a few seconds. This patch resolves the problem Zwane ran into. Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* mm: re-architect the VM_UNPAGED logicLinus Torvalds2005-11-281-12/+2Star
| | | | | | | | | | | | | | | | This replaces the (in my opinion horrible) VM_UNMAPPED logic with very explicit support for a "remapped page range" aka VM_PFNMAP. It allows a VM area to contain an arbitrary range of page table entries that the VM never touches, and never considers to be normal pages. Any user of "remap_pfn_range()" automatically gets this new functionality, and doesn't even have to mark the pages reserved or indeed mark them any other way. It just works. As a side effect, doing mmap() on /dev/mem works for arbitrary ranges. Sparc update from David in the next commit. Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] unpaged: anon in VM_UNPAGEDHugh Dickins2005-11-221-2/+5
| | | | | | | | | | | | | | | | | | | | | | copy_one_pte needs to copy the anonymous COWed pages in a VM_UNPAGED area, zap_pte_range needs to free them, do_wp_page needs to COW them: just like ordinary pages, not like the unpaged. But recognizing them is a little subtle: because PageReserved is no longer a condition for remap_pfn_range, we can now mmap all of /dev/mem (whether the distro permits, and whether it's advisable on this or that architecture, is another matter). So if we can see a PageAnon, it may not be ours to mess with (or may be ours from elsewhere in the address space). I suspect there's an entertaining insoluble self-referential problem here, but the page_is_anon function does a good practical job, and MAP_PRIVATE PROT_WRITE VM_UNPAGED will always be an odd choice. In updating the comment on page_address_in_vma, noticed a potential NULL dereference, in a path we don't actually take, but fixed it. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] unpaged: VM_NONLINEAR VM_RESERVEDHugh Dickins2005-11-221-10/+5Star
| | | | | | | | | | | | | | | | There's one peculiar use of VM_RESERVED which the previous patch left behind: because VM_NONLINEAR's try_to_unmap_cluster uses vm_private_data as a swapout cursor, but should never meet VM_RESERVED vmas, it was a way of extending VM_NONLINEAR to VM_RESERVED vmas using vm_private_data for some other purpose. But that's an empty set - they don't have the populate function required. So just throw away those VM_RESERVED tests. But one more interesting in rmap.c has to go too: try_to_unmap_one will want to swap out an anonymous page from VM_RESERVED or VM_UNPAGED area. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: update comments to pte lockHugh Dickins2005-10-301-5/+5
| | | | | | | | Updated several references to page_table_lock in common code comments. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: fix rss and mmlist lockingHugh Dickins2005-10-301-1/+2
| | | | | | | | | | | | | | | | | | A couple of oddities were guarded by page_table_lock, no longer properly guarded when that is split. The mm_counters of file_rss and anon_rss: make those an atomic_t, or an atomic64_t if the architecture supports it, in such a case. Definitions by courtesy of Christoph Lameter: who spent considerable effort on more scalable ways of counting, but found insufficient benefit in practice. And adding an mm with swap to the mmlist for swapoff: the list is well- guarded by its own lock, but the list_empty check now has to be repeated inside it. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: split page table lockHugh Dickins2005-10-301-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with a many-threaded application which concurrently initializes different parts of a large anonymous area. This patch corrects that, by using a separate spinlock per page table page, to guard the page table entries in that page, instead of using the mm's single page_table_lock. (But even then, page_table_lock is still used to guard page table allocation, and anon_vma allocation.) In this implementation, the spinlock is tucked inside the struct page of the page table page: with a BUILD_BUG_ON in case it overflows - which it would in the case of 32-bit PA-RISC with spinlock debugging enabled. Splitting the lock is not quite for free: another cacheline access. Ideally, I suppose we would use split ptlock only for multi-threaded processes on multi-cpu machines; but deciding that dynamically would have its own costs. So for now enable it by config, at some number of cpus - since the Kconfig language doesn't support inequalities, let preprocessor compare that with NR_CPUS. But I don't think it's worth being user-configurable: for good testing of both split and unsplit configs, split now at 4 cpus, and perhaps change that to 8 later. There is a benefit even for singly threaded processes: kswapd can be attacking one part of the mm while another part is busy faulting. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: rmap with inner ptlockHugh Dickins2005-10-301-55/+54Star
| | | | | | | | | | | | | | | rmap's page_check_address descend without page_table_lock. First just pte_offset_map in case there's no pte present worth locking for, then take page_table_lock for the full check, and pass ptl back to caller in the same style as pte_offset_map_lock. __xip_unmap, page_referenced_one and try_to_unmap_one use pte_unmap_unlock. try_to_unmap_cluster also. page_check_address reformatted to avoid progressive indentation. No use is made of its one error code, return NULL when it fails. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: update_hiwaters just in timeHugh Dickins2005-10-301-0/+6
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | update_mem_hiwater has attracted various criticisms, in particular from those concerned with mm scalability. Originally it was called whenever rss or total_vm got raised. Then many of those callsites were replaced by a timer tick call from account_system_time. Now Frank van Maarseveen reports that to be found inadequate. How about this? Works for Frank. Replace update_mem_hiwater, a poor combination of two unrelated ops, by macros update_hiwater_rss and update_hiwater_vm. Don't attempt to keep mm->hiwater_rss up to date at timer tick, nor every time we raise rss (usually by 1): those are hot paths. Do the opposite, update only when about to lower rss (usually by many), or just before final accounting in do_exit. Handle mm->hiwater_vm in the same way, though it's much less of an issue. Demand that whoever collects these hiwater statistics do the work of taking the maximum with rss or total_vm. And there has been no collector of these hiwater statistics in the tree. The new convention needs an example, so match Frank's usage by adding a VmPeak line above VmSize to /proc/<pid>/status, and also a VmHWM line above VmRSS (High-Water-Mark or High-Water-Memory). There was a particular anomaly during mremap move, that hiwater_vm might be captured too high. A fleeting such anomaly remains, but it's quickly corrected now, whereas before it would stick. What locking? None: if the app is racy then these statistics will be racy, it's not worth any overhead to make them exact. But whenever it suits, hiwater_vm is updated under exclusive mmap_sem, and hiwater_rss under page_table_lock (for now) or with preemption disabled (later on): without going to any trouble, minimize the time between reading current values and updating, to minimize those occasions when a racing thread bumps a count up and back down in between. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] core remove PageReservedNick Piggin2005-10-301-10/+4Star
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Remove PageReserved() calls from core code by tightening VM_RESERVED handling in mm/ to cover PageReserved functionality. PageReserved special casing is removed from get_page and put_page. All setting and clearing of PageReserved is retained, and it is now flagged in the page_alloc checks to help ensure we don't introduce any refcount based freeing of Reserved pages. MAP_PRIVATE, PROT_WRITE of VM_RESERVED regions is tentatively being deprecated. We never completely handled it correctly anyway, and is be reintroduced in future if required (Hugh has a proof of concept). Once PageReserved() calls are removed from kernel/power/swsusp.c, and all arch/ and driver code, the Set and Clear calls, and the PG_reserved bit can be trivially removed. Last real user of PageReserved is swsusp, which uses PageReserved to determine whether a struct page points to valid memory or not. This still needs to be addressed (a generic page_is_ram() should work). A last caveat: the ZERO_PAGE is now refcounted and managed with rmap (and thus mapcounted and count towards shared rss). These writes to the struct page could cause excessive cacheline bouncing on big systems. There are a number of ways this could be addressed if it is an issue. Signed-off-by: Nick Piggin <npiggin@suse.de> Refcount bug fix for filemap_xip.c Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: rss = file_rss + anon_rssHugh Dickins2005-10-301-5/+3Star
| | | | | | | | | | | | | | | | I was lazy when we added anon_rss, and chose to change as few places as possible. So currently each anonymous page has to be counted twice, in rss and in anon_rss. Which won't be so good if those are atomic counts in some configurations. Change that around: keep file_rss and anon_rss separately, and add them together (with get_mm_rss macro) when the total is needed - reading two atomics is much cheaper than updating two atomics. And update anon_rss upfront, typically in memory.c, not tucked away in page_add_anon_rmap. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] swaptoken tuningRik Van Riel2005-10-301-1/+5
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | It turns out that the original swap token implementation, by Song Jiang, only enforced the swap token while the task holding the token is handling a page fault. This patch approximates that, without adding an additional flag to the mm_struct, by checking whether the mm->mmap_sem is held for reading, like the page fault code does. This patch has the effect of automatically, and gradually, disabling the enforcement of the swap token when there is little or no paging going on, and "turning up" the intensity of the swap token code the more the task holding the token is thrashing. Thanks to Song Jiang for pointing out this aspect of the token based thrashing control concept. The new code shows a slight degradation over the old swap token code, but still a big win over running without the swap token. 2.6.12+ swap token disabled $ for i in `seq 10` ; do /usr/bin/time ./qsbench -n 30000000 -p 3 ; done 101.74user 23.13system 8:26.91elapsed 24%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (38597major+430315minor)pagefaults 0swaps 101.98user 24.91system 8:03.06elapsed 26%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (33939major+430457minor)pagefaults 0swaps 101.93user 22.12system 7:34.90elapsed 27%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (33166major+421267minor)pagefaults 0swaps 101.82user 22.38system 8:31.40elapsed 24%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (39338major+433262minor)pagefaults 0swaps 2.6.12+ swap token enabled, timeout 300 seconds $ for i in `seq 4` ; do /usr/bin/time ./qsbench -n 30000000 -p 3 ; done 102.58user 16.08system 3:41.44elapsed 53%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (19707major+285786minor)pagefaults 0swaps 102.07user 19.56system 4:00.64elapsed 50%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (19012major+299259minor)pagefaults 0swaps 102.64user 18.25system 4:07.31elapsed 48%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (21990major+304831minor)pagefaults 0swaps 101.39user 19.41system 5:15.81elapsed 38%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (24850major+323321minor)pagefaults 0swaps 2.6.12+ with new swap token code, timeout 300 seconds $ for i in `seq 4` ; do /usr/bin/time ./qsbench -n 30000000 -p 3 ; done 101.87user 24.66system 5:53.20elapsed 35%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (26848major+363497minor)pagefaults 0swaps 102.83user 19.95system 4:17.25elapsed 47%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (19946major+305722minor)pagefaults 0swaps 102.09user 19.46system 5:12.57elapsed 38%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (25461major+334994minor)pagefaults 0swaps 101.67user 20.61system 4:52.97elapsed 41%CPU (0avgtext+0avgdata 0maxresident)k 0inputs+0outputs (22190major+329508minor)pagefaults 0swaps Signed-off-by: Rik Van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: cleanup rmapNick Piggin2005-09-051-5/+1Star
| | | | | | | | Thanks to Bill Irwin for pointing this out. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: micro-optimise rmapNick Piggin2005-09-051-10/+11
| | | | | | | | | | Microoptimise page_add_anon_rmap. Although these expressions are used only in the taken branch of the if() statement, the compiler can't reorder them inside because atomic_inc_and_test is a barrier. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: comment rmapNick Piggin2005-09-051-0/+2
| | | | | | | | | Just be clear that VM_RESERVED pages here are a bug, and the test is not there because they are expected. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] rmap: don't test rssHugh Dickins2005-09-051-6/+1Star
| | | | | | | | | | | Remove the three get_mm_counter(mm, rss) tests from rmap.c: there was a time when testing rss was important to avoid a particular race between dup_mmap and the anonmm rmap; but now it's just a rather silly pseudo- optimization, made even more obscure by the get_mm_counter macro. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] swap: swap_lock replace list+deviceHugh Dickins2005-09-051-2/+1Star
| | | | | | | | | | | | | | | | | | | | | | | | | The idea of a swap_device_lock per device, and a swap_list_lock over them all, is appealing; but in practice almost every holder of swap_device_lock must already hold swap_list_lock, which defeats the purpose of the split. The only exceptions have been swap_duplicate, valid_swaphandles and an untrodden path in try_to_unuse (plus a few places added in this series). valid_swaphandles doesn't show up high in profiles, but swap_duplicate does demand attention. However, with the hold time in get_swap_pages so much reduced, I've not yet found a load and set of swap device priorities to show even swap_duplicate benefitting from the split. Certainly the split is mere overhead in the common case of a single swap device. So, replace swap_list_lock and swap_device_lock by spinlock_t swap_lock (generally we seem to prefer an _ in the name, and not hide in a macro). If someone can show a regression in swap_duplicate, then probably we should add a hashlock for the swap_map entries alone (shorts being anatomic), so as to help the case of the single swap device too. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] xip: fs/mm: execute in placeCarsten Otte2005-06-241-2/+2
| | | | | | | | | | | | | | | | - generic_file* file operations do no longer have a xip/non-xip split - filemap_xip.c implements a new set of fops that require get_xip_page aop to work proper. all new fops are exported GPL-only (don't like to see whatever code use those except GPL modules) - __xip_unmap now uses page_check_address, which is no longer static in rmap.c, and defined in linux/rmap.h - mm/filemap.h is now much more clean, plainly having just Linus' inline funcs moved here from filemap.c - fix includes in filemap_xip to make it build cleanly on i386 Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] can_share_swap_page: use page_mapcountHugh Dickins2005-06-221-21/+0Star
| | | | | | | | | | | | | | | | | | | | | | | | | | Remember that ironic get_user_pages race? when the raised page_count on a page swapped out led do_wp_page to decide that it had to copy on write, so substituted a different page into userspace. 2.6.7 onwards have Andrea's solution, where try_to_unmap_one backs out if it finds page_count raised. Which works, but is unsatisfying (rmap.c has no other page_count heuristics), and was found a few months ago to hang an intensive page migration test. A year ago I was hesitant to engage page_mapcount, now it seems the right fix. So remove the page_count hack from try_to_unmap_one; and use activate_page in unuse_mm when dropping lock, to replace its secondary effect of helping swapoff to make progress in that case. Simplify can_share_swap_page (now called only on anonymous pages) to check page_mapcount + page_swapcount == 1: still needs the page lock to stabilize their (pessimistic) sum, but does not need swapper_space.tree_lock for that. In do_swap_page, move swap_free and unlock_page below page_add_anon_rmap, to keep sum on the high side, and correct when can_share_swap_page called. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] try_to_unmap_cluster() passes out-of-bounds pte to pte_unmap()William Lee Irwin III2005-05-251-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | try_to_unmap_cluster() does: for (pte = pte_offset_map(pmd, address); address < end; pte++, address += PAGE_SIZE) { ... } pte_unmap(pte); It may take a little staring to notice, but pte can actually fall off the end of the pte page in this iteration, which makes life difficult for kmap_atomic() and the users not expecting it to BUG(). Of course, we're somewhat lucky in that arithmetic elsewhere in the function guarantees that at least one iteration is made, lest this force larger rearrangements to be made. This issue and patch also apply to non-mm mainline and with trivial adjustments, at least two related kernels. Discovered during internal testing at Oracle. Signed-off-by: William Irwin <wli@holomorphy.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: fix rss counter being incremented when unmappingBjorn Steinbrink2005-05-171-1/+1
| | | | | | | | | | This patch fixes a bug introduced by the "mm counter operations through macros" patch, which replaced a decrement operation in with an increment macro in try_to_unmap_one(). Signed-off-by: Björn Steinbrink <B.Steinbrink@gmx.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] mm: rmap.c cleanupNikita Danilov2005-05-011-63/+50Star
| | | | | | | | | | | | | | | | | mm/rmap.c:page_referenced_one() and mm/rmap.c:try_to_unmap_one() contain identical code that - takes mm->page_table_lock; - drills through page tables; - checks that correct pte is reached. Coalesce this into page_check_address() Signed-off-by: Nikita Danilov <nikita@clusterfs.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* Linux-2.6.12-rc2Linus Torvalds2005-04-171-0/+862
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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