- 30 Oct, 2005 40 commits
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Hugh Dickins authored
Second step in pushing down the page_table_lock. Remove the temporary bridging hack from __pud_alloc, __pmd_alloc, __pte_alloc: expect callers not to hold page_table_lock, whether it's on init_mm or a user mm; take page_table_lock internally to check if a racing task already allocated. Convert their callers from common code. But avoid coming back to change them again later: instead of moving the spin_lock(&mm->page_table_lock) down, switch over to new macros pte_alloc_map_lock and pte_unmap_unlock, which encapsulate the mapping+locking and unlocking+unmapping together, and in the end may use alternatives to the mm page_table_lock itself. These callers all hold mmap_sem (some exclusively, some not), so at no level can a page table be whipped away from beneath them; and pte_alloc uses the "atomic" pmd_present to test whether it needs to allocate. It appears that on all arches we can safely descend without page_table_lock. Signed-off-by:
Hugh Dickins <hugh@veritas.com> Signed-off-by:
Andrew Morton <akpm@osdl.org> Signed-off-by:
Linus Torvalds <torvalds@osdl.org>
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Hugh Dickins authored
It seems odd to me that, whereas pud_alloc and pmd_alloc test inline, only calling out-of-line __pud_alloc __pmd_alloc if allocation needed, pte_alloc_map and pte_alloc_kernel are entirely out-of-line. Though it does add a little to kernel size, change them to macros testing inline, calling __pte_alloc or __pte_alloc_kernel to allocate out-of-line. Mark none of them as fastcalls, leave that to CONFIG_REGPARM or not. It also seems more natural for the out-of-line functions to leave the offset calculation and map to the inline, which has to do it anyway for the common case. At least mremap move wants __pte_alloc without _map. Macros rather than inline functions, certainly to avoid the header file issues which arise from CONFIG_HIGHPTE needing kmap_types.h, but also in case any architectures I haven't built would have other such problems. Signed-off-by:
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Hugh Dickins authored
First step in pushing down the page_table_lock. init_mm.page_table_lock has been used throughout the architectures (usually for ioremap): not to serialize kernel address space allocation (that's usually vmlist_lock), but because pud_alloc,pmd_alloc,pte_alloc_kernel expect caller holds it. Reverse that: don't lock or unlock init_mm.page_table_lock in any of the architectures; instead rely on pud_alloc,pmd_alloc,pte_alloc_kernel to take and drop it when allocating a new one, to check lest a racing task already did. Similarly no page_table_lock in vmalloc's map_vm_area. Some temporary ugliness in __pud_alloc and __pmd_alloc: since they also handle user mms, which are converted only by a later patch, for now they have to lock differently according to whether or not it's init_mm. If sources get muddled, there's a danger that an arch source taking init_mm.page_table_lock will be mixed with common source also taking it (or neither take it). So break the rules and make another change, which should break the build for such a mismatch: remove the redundant mm arg from pte_alloc_kernel (ppc64 scrapped its distinct ioremap_mm in 2.6.13). Exceptions: arm26 used pte_alloc_kernel on user mm, now pte_alloc_map; ia64 used pte_alloc_map on init_mm, now pte_alloc_kernel; parisc had bad args to pmd_alloc and pte_alloc_kernel in unused USE_HPPA_IOREMAP code; ppc64 map_io_page forgot to unlock on failure; ppc mmu_mapin_ram and ppc64 im_free took page_table_lock for no good reason. Signed-off-by:
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Hugh Dickins authored
ia64 has expand_backing_store function for growing its Register Backing Store vma upwards. But more complete code for this purpose is found in the CONFIG_STACK_GROWSUP part of mm/mmap.c. Uglify its #ifdefs further to provide expand_upwards for ia64 as well as expand_stack for parisc. The Register Backing Store vma should be marked VM_ACCOUNT. Implement the intention of growing it only a page at a time, instead of passing an address outside of the vma to handle_mm_fault, with unknown consequences. Signed-off-by:
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Hugh Dickins authored
Slight and timid rearrangement of mm_struct: hiwater_rss and hiwater_vm were tacked on the end, but it seems better to keep them near _file_rss, _anon_rss and total_vm, in the same cacheline on those arches verified. There are likely to be more profitable rearrangements, but less obvious (is it good or bad that saved_auxv[AT_VECTOR_SIZE] isolates cpu_vm_mask and context from many others?), needing serious instrumentation. Signed-off-by:
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Hugh Dickins authored
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:
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Hugh Dickins authored
There used to be just one call to zap_pte, but it shouldn't be inline now there are two. Check for the common case pte_none before calling, and move its rss accounting up into install_page or install_file_pte - which helps the next patch. Signed-off-by:
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Hugh Dickins authored
Cleanup: relieve do_mremap from its surfeit of current->mms. Signed-off-by:
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Hugh Dickins authored
Small adjustment: do_swap_page should report its !pte_same race as a major fault if it had to read into swap cache, because whatever raced with it will have found page already in cache and reported minor fault. Signed-off-by:
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Hugh Dickins authored
Small adjustment: zap_pte_range decrement its rss counts from 0 then finally add, avoiding negations - we don't have or need a sub_mm_rss. Signed-off-by:
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Hugh Dickins authored
Small adjustment, following Nick's suggestion: it's more straightforward for copy_pte_range to let copy_one_pte do the rss incrementation, than use an index it passed back. Saves a #define, and 16 bytes of .text. Signed-off-by:
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Nick Piggin authored
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:
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Hugh Dickins authored
Please, please now delete the Atari CONFIG_STRAM_SWAP code. It may be excellent and ingenious code, but its reference to swap_vfsmnt betrays that it hasn't been built since 2.5.1 (four years old come December), it's delving deep into matters which are the preserve of core mm code, its only purpose is to give the more conscientious mm guys an anxiety attack from time to time; yet we keep on breaking it more and more. If you want to use RAM for swap, then if the MTD driver does not already provide just what you need, I'm sure David could be persuaded to add the extra. But you'd also like to be able to allocate extents of that swap for other use: we can give you a core interface for that if you need. But unbuilt for four years suggests to me that there's no need at all. I cannot swear the patch below won't break your build, but believe so. Signed-off-by:
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Hugh Dickins authored
The sh64 hugetlbpage.c seems to be erroneous, left over from a bygone age, clashing with the common hugetlb.c. Replace it by a copy of the sh hugetlbpage.c. Except, delete that mk_pte_huge macro neither uses. Signed-off-by:
Paul Mundt <lethal@linux-sh.org> Signed-off-by:
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Hugh Dickins authored
One anomaly remains from when Andrea rationalized the responsibilities of mmap_sem and page_table_lock: in dup_mmap we add vmas to the child holding its page_table_lock, but not the mmap_sem which normally guards the vma list and rbtree. Which could be an issue for unuse_mm: though since it just walks down the list (today with page_table_lock, tomorrow not), it's probably okay. Will need a memory barrier? Oh, keep it simple, Nick and I agreed, no harm in taking child's mmap_sem here. Signed-off-by:
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Hugh Dickins authored
Use the parent's oldmm throughout dup_mmap, instead of perversely going back to current->mm. (Can you hear the sigh of relief from those mpnts? Usually I squash them, but not today.) Signed-off-by:
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Hugh Dickins authored
tlb_finish_mmu used to batch zap_pte_range's update of mm rss, which may be worthwhile if the mm is contended, and would reduce atomic operations if the counts were atomic. Let zap_pte_range now batch its updates to file_rss and anon_rss, per page-table in case we drop the lock outside; and copy_pte_range batch them too. Signed-off-by:
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Hugh Dickins authored
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:
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Hugh Dickins authored
How is anon_rss initialized? In dup_mmap, and by mm_alloc's memset; but that's not so good if an mm_counter_t is a special type. And how is rss initialized? By set_mm_counter, all over the place. Come on, we just need to initialize them both at once by set_mm_counter in mm_init (which follows the memcpy when forking). Signed-off-by:
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Hugh Dickins authored
zap_pte_range has been counting the pages it frees in tlb->freed, then tlb_finish_mmu has used that to update the mm's rss. That got stranger when I added anon_rss, yet updated it by a different route; and stranger when rss and anon_rss became mm_counters with special access macros. And it would no longer be viable if we're relying on page_table_lock to stabilize the mm_counter, but calling tlb_finish_mmu outside that lock. Remove the mmu_gather's freed field, let tlb_finish_mmu stick to its own business, just decrement the rss mm_counter in zap_pte_range (yes, there was some point to batching the update, and a subsequent patch restores that). And forget the anal paranoia of first reading the counter to avoid going negative - if rss does go negative, just fix that bug. Remove the mmu_gather's flushes and avoided_flushes from arm and arm26: no use was being made of them. But arm26 alone was actually using the freed, in the way some others use need_flush: give it a need_flush. arm26 seems to prefer spaces to tabs here: respect that. Signed-off-by:
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Hugh Dickins authored
tlb_is_full_mm? What does that mean? The TLB is full? No, it means that the mm's last user has gone and the whole mm is being torn down. And it's an inline function because sparc64 uses a different (slightly better) "tlb_frozen" name for the flag others call "fullmm". And now the ptep_get_and_clear_full macro used in zap_pte_range refers directly to tlb->fullmm, which would be wrong for sparc64. Rather than correct that, I'd prefer to scrap tlb_is_full_mm altogether, and change sparc64 to just use the same poor name as everyone else - is that okay? Signed-off-by:
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Hugh Dickins authored
tlb_gather_mmu dates from before kernel preemption was allowed, and uses smp_processor_id or __get_cpu_var to find its per-cpu mmu_gather. That works because it's currently only called after getting page_table_lock, which is not dropped until after the matching tlb_finish_mmu. But don't rely on that, it will soon change: now disable preemption internally by proper get_cpu_var in tlb_gather_mmu, put_cpu_var in tlb_finish_mmu. Signed-off-by:
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Hugh Dickins authored
Speeding up mremap's moving of ptes has never been a priority, but the locking will get more complicated shortly, and is already too baroque. Scrap the current one-by-one moving, do an extent at a time: curtailed by end of src and dst pmds (have to use PMD_SIZE: the way pmd_addr_end gets elided doesn't match this usage), and by latency considerations. One nice property of the old method is lost: it never allocated a page table unless absolutely necessary, so you could free empty page tables by mremapping to and fro. Whereas this way, it allocates a dst table wherever there was a src table. I keep diving in to reinstate the old behaviour, then come out preferring not to clutter how it now is. Signed-off-by:
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Hugh Dickins authored
Impose a little more consistency on the page fault handlers do_wp_page, do_swap_page, do_anonymous_page, do_no_page, do_file_page: why not pass their arguments in the same order, called the same names? break_cow is all very well, but what it did was inlined elsewhere: easier to compare if it's brought back into do_wp_page. do_file_page's fallback to do_no_page dates from a time when we were testing pte_file by using it wherever possible: currently it's peculiar to nonlinear vmas, so just check that. BUG_ON if not? Better not, it's probably page table corruption, so just show the pte: hmm, there's a pte_ERROR macro, let's use that for do_wp_page's invalid pfn too. Hah! Someone in the ppc64 world noticed pte_ERROR was unused so removed it: restored (and say "pud" not "pmd" in its pud_ERROR). Signed-off-by:
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Hugh Dickins authored
exit_mmap resets various mm_struct fields, but the mm is well on its way out, and none of those fields matter by this point. Signed-off-by:
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Hugh Dickins authored
Divide remove_vm_struct into two parts: first anon_vma_unlink plus unlink_file_vma, to unlink the vma from the list and tree by which rmap or vmtruncate might find it; then remove_vma to close, fput and free. The intention here is to do the anon_vma_unlink and unlink_file_vma earlier, in free_pgtables before freeing any page tables: so we can be sure that any page tables traversed by rmap and vmtruncate are stable (and other, ordinary cases are stabilized by holding mmap_sem). This will be crucial to traversing pgd,pud,pmd without page_table_lock. But testing the split-out patch showed that lifting the page_table_lock is symbiotically necessary to make this change - the lock ordering is wrong to move those unlinks into free_pgtables while it's under ptlock. Signed-off-by:
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Hugh Dickins authored
unmap_vma doesn't amount to much, let's put it inside unmap_vma_list. Except it doesn't unmap anything, unmap_region just did the unmapping: rename it to remove_vma_list. Signed-off-by:
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Hugh Dickins authored
The original vm_stat_account has fallen into disuse, with only one user, and only one user of vm_stat_unaccount. It's easier to keep track if we convert them all to __vm_stat_account, then free it from its __shackles. Signed-off-by:
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Hugh Dickins authored
do_anonymous_page's pte_wrprotect causes some confusion: in such a case, vm_page_prot must already be forcing COW, so must omit write permission, and so the pte_wrprotect is redundant. Replace it by a comment to that effect, and reword the comment on unuse_pte which also caused confusion. Signed-off-by:
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Hugh Dickins authored
zap_pte_range already avoids wasting time to mark_page_accessed on anon pages: it can also skip anon set_page_dirty - the page only needs to be marked dirty if shared with another mm, but that will say pte_dirty too. Signed-off-by:
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Hugh Dickins authored
Use latency breaking in msync_pte_range like that in copy_pte_range, instead of the ugly CONFIG_PREEMPT filemap_msync alternatives. Signed-off-by:
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Hugh Dickins authored
My latency breaking in copy_pte_range didn't work as intended: instead of checking at regularish intervals, after the first interval it checked every time around the loop, too impatient to be preempted. Fix that. Signed-off-by:
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Christoph Lameter authored
This patch adds some stack dumps if the slab logic is processing slab blocks from the wrong node. This is necessary in order to detect situations as encountered by Petr. Signed-off-by:
Christoph Lameter <clameter@sgi.com> Signed-off-by:
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Lee Schermerhorn authored
Martin Hicks' page cache reclaim patch added the 'may_swap' flag to the scan_control struct; and modified shrink_list() not to add anon pages to the swap cache if may_swap is not asserted. Ref: http://marc.theaimsgroup.com/?l=linux-mm&m=111461480725322&w=4 However, further down, if the page is mapped, shrink_list() calls try_to_unmap() which will call try_to_unmap_one() via try_to_unmap_anon (). try_to_unmap_one() will BUG_ON() an anon page that is NOT in the swap cache. Martin says he never encountered this path in his testing, but agrees that it might happen. This patch modifies shrink_list() to skip anon pages that are not already in the swap cache when !may_swap, rather than just not adding them to the cache. Signed-off-by:
Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by:
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OGAWA Hirofumi authored
This is not problem actually, but sync_page_range() is using for exported function to filesystems. The msync_xxx is more readable at least to me. Signed-off-by:
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Acked-by:
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Andi Kleen authored
Most of them can never be triggered and were only for development. Signed-off-by:
"Andi Kleen" <ak@suse.de> Signed-off-by:
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Andi Kleen authored
The NUMA policy code predated nodemask_t so it used open coded bitmaps. Convert everything to nodemask_t. Big patch, but shouldn't have any actual behaviour changes (except I removed one unnecessary check against node_online_map and one unnecessary BUG_ON) Signed-off-by:
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Seth, Rohit authored
Set the low water mark for hot pages in pcp to zero. (akpm: for the life of me I cannot remember why we created pcp->low. Neither can Martin and the changelog is silent. Maybe it was just a brainfart, but I have this feeling that there was a reason. If not, we should remove the fields completely. We'll see.) Signed-off-by:
Rohit Seth <rohit.seth@intel.com> Cc: <linux-mm@kvack.org> Signed-off-by:
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Seth, Rohit authored
Increase the page allocator's per-cpu magazines from 1/4MB to 1/2MB. Over 100+ runs for a workload, the difference in mean is about 2%. The best results for both are almost same. Though the max variation in results with 1/2MB is only 2.2%, whereas with 1/4MB it is 12%. Signed-off-by:
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Rik Van Riel authored
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:
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