- 26 9月, 2006 4 次提交
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由 Rolf Eike Beer 提交于
These functions are already documented quite well with long comments. Now add kerneldoc style header to make this turn up in everyones favorite doc format. Signed-off-by: NRolf Eike Beer <eike-kernel@sf-tec.de> Cc: "Randy.Dunlap" <rdunlap@xenotime.net> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Peter Zijlstra 提交于
Wrt. the recent modifications in do_wp_page() Hugh Dickins pointed out: "I now realize it's right to the first order (normal case) and to the second order (ptrace poke), but not to the third order (ptrace poke anon page here to be COWed - perhaps can't occur without intervening mprotects)." This patch restores the old COW behaviour for anonymous pages. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: NHugh Dickins <hugh@veritas.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Peter Zijlstra 提交于
Now that we can detect writers of shared mappings, throttle them. Avoids OOM by surprise. Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Peter Zijlstra 提交于
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: NPeter Zijlstra <a.p.zijlstra@chello.nl> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: NDavid Howells <dhowells@redhat.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 15 7月, 2006 2 次提交
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由 Shailabh Nagar 提交于
Unlike earlier iterations of the delay accounting patches, now delays are only collected for the actual I/O waits rather than try and cover the delays seen in I/O submission paths. Account separately for block I/O delays incurred as a result of swapin page faults whose frequency can be affected by the task/process' rss limit. Hence swapin delays can act as feedback for rss limit changes independent of I/O priority changes. Signed-off-by: NShailabh Nagar <nagar@watson.ibm.com> Signed-off-by: NBalbir Singh <balbir@in.ibm.com> Cc: Jes Sorensen <jes@sgi.com> Cc: Peter Chubb <peterc@gelato.unsw.edu.au> Cc: Erich Focht <efocht@ess.nec.de> Cc: Levent Serinol <lserinol@gmail.com> Cc: Jay Lan <jlan@engr.sgi.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Anil Keshavamurthy 提交于
There is a race condition that showed up in a threaded JIT environment. The situation is that a process with a JIT code page forks, so the page is marked read-only, then some threads are created in the child. One of the threads attempts to add a new code block to the JIT page, so a copy-on-write fault is taken, and the kernel allocates a new page, copies the data, installs the new pte, and then calls lazy_mmu_prot_update() to flush caches to make sure that the icache and dcache are in sync. Unfortunately, the other thread runs right after the new pte is installed, but before the caches have been flushed. It tries to execute some old JIT code that was already in this page, but it sees some garbage in the i-cache from the previous users of the new physical page. Fix: we must make the caches consistent before installing the pte. This is an ia64 only fix because lazy_mmu_prot_update() is a no-op on all other architectures. Signed-off-by: NAnil Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: NTony Luck <tony.luck@intel.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 11 7月, 2006 1 次提交
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由 Adrian Bunk 提交于
This patch marks an unused export as EXPORT_UNUSED_SYMBOL. Signed-off-by: NAdrian Bunk <bunk@stusta.de> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 04 7月, 2006 1 次提交
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由 Ingo Molnar 提交于
Teach special (recursive) locking code to the lock validator. Has no effect on non-lockdep kernels. Signed-off-by: NIngo Molnar <mingo@elte.hu> Signed-off-by: NArjan van de Ven <arjan@linux.intel.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 01 7月, 2006 2 次提交
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由 Christoph Lameter 提交于
The remaining counters in page_state after the zoned VM counter patches have been applied are all just for show in /proc/vmstat. They have no essential function for the VM. We use a simple increment of per cpu variables. In order to avoid the most severe races we disable preempt. Preempt does not prevent the race between an increment and an interrupt handler incrementing the same statistics counter. However, that race is exceedingly rare, we may only loose one increment or so and there is no requirement (at least not in kernel) that the vm event counters have to be accurate. In the non preempt case this results in a simple increment for each counter. For many architectures this will be reduced by the compiler to a single instruction. This single instruction is atomic for i386 and x86_64. And therefore even the rare race condition in an interrupt is avoided for both architectures in most cases. The patchset also adds an off switch for embedded systems that allows a building of linux kernels without these counters. The implementation of these counters is through inline code that hopefully results in only a single instruction increment instruction being emitted (i386, x86_64) or in the increment being hidden though instruction concurrency (EPIC architectures such as ia64 can get that done). Benefits: - VM event counter operations usually reduce to a single inline instruction on i386 and x86_64. - No interrupt disable, only preempt disable for the preempt case. Preempt disable can also be avoided by moving the counter into a spinlock. - Handling is similar to zoned VM counters. - Simple and easily extendable. - Can be omitted to reduce memory use for embedded use. References: RFC http://marc.theaimsgroup.com/?l=linux-kernel&m=113512330605497&w=2 RFC http://marc.theaimsgroup.com/?l=linux-kernel&m=114988082814934&w=2 local_t http://marc.theaimsgroup.com/?l=linux-kernel&m=114991748606690&w=2 V2 http://marc.theaimsgroup.com/?t=115014808400007&r=1&w=2 V3 http://marc.theaimsgroup.com/?l=linux-kernel&m=115024767022346&w=2 V4 http://marc.theaimsgroup.com/?l=linux-kernel&m=115047968808926&w=2Signed-off-by: NChristoph Lameter <clameter@sgi.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Christoph Lameter 提交于
Conversion of nr_page_table_pages to a per zone counter [akpm@osdl.org: bugfix] Signed-off-by: NChristoph Lameter <clameter@sgi.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 23 6月, 2006 3 次提交
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由 David Howells 提交于
Add a new VMA operation to notify a filesystem or other driver about the MMU generating a fault because userspace attempted to write to a page mapped through a read-only PTE. This facility permits the filesystem or driver to: (*) Implement storage allocation/reservation on attempted write, and so to deal with problems such as ENOSPC more gracefully (perhaps by generating SIGBUS). (*) Delay making the page writable until the contents have been written to a backing cache. This is useful for NFS/AFS when using FS-Cache/CacheFS. It permits the filesystem to have some guarantee about the state of the cache. (*) Account and limit number of dirty pages. This is one piece of the puzzle needed to make shared writable mapping work safely in FUSE. Needed by cachefs (Or is it cachefiles? Or fscache? <head spins>). At least four other groups have stated an interest in it or a desire to use the functionality it provides: FUSE, OCFS2, NTFS and JFFS2. Also, things like EXT3 really ought to use it to deal with the case of shared-writable mmap encountering ENOSPC before we permit the page to be dirtied. From: Peter Zijlstra <a.p.zijlstra@chello.nl> get_user_pages(.write=1, .force=1) can generate COW hits on read-only shared mappings, this patch traps those as mkpage_write candidates and fails to handle them the old way. Signed-off-by: NDavid Howells <dhowells@redhat.com> Cc: Miklos Szeredi <miklos@szeredi.hu> Cc: Joel Becker <Joel.Becker@oracle.com> Cc: Mark Fasheh <mark.fasheh@oracle.com> Cc: Anton Altaparmakov <aia21@cantab.net> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Christoph Lameter 提交于
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: NHugh Dickins <hugh@veritas.com> Acked-by: NMartin Schwidefsky <schwidefsky@de.ibm.com> Signed-off-by: NHugh Dickins <hugh@veritas.com> Signed-off-by: NChristoph Lameter <clameter@engr.sgi.com> Signed-off-by: NIngo Molnar <mingo@elte.hu> From: Hugh Dickins <hugh@veritas.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Christoph Lameter 提交于
It is better to redo the complete fault if do_swap_page() finds that the page is not in PageSwapCache() because the page migration code may have replaced the swap pte already with a pte pointing to valid memory. do_swap_page() may interpret an invalid swap entry without this patch because we do not reload the pte if we are looping back. The page migration code may already have reused the swap entry referenced by our local swp_entry. Signed-off-by: NChristoph Lameter <clameter@sgi.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 01 4月, 2006 1 次提交
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由 OGAWA Hirofumi 提交于
The boot cmdline is parsed in parse_early_param() and parse_args(,unknown_bootoption). And __setup() is used in obsolete_checksetup(). start_kernel() -> parse_args() -> unknown_bootoption() -> obsolete_checksetup() If __setup()'s callback (->setup_func()) returns 1 in obsolete_checksetup(), obsolete_checksetup() thinks a parameter was handled. If ->setup_func() returns 0, obsolete_checksetup() tries other ->setup_func(). If all ->setup_func() that matched a parameter returns 0, a parameter is seted to argv_init[]. Then, when runing /sbin/init or init=app, argv_init[] is passed to the app. If the app doesn't ignore those arguments, it will warning and exit. This patch fixes a wrong usage of it, however fixes obvious one only. Signed-off-by: NOGAWA Hirofumi <hirofumi@mail.parknet.co.jp> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 27 3月, 2006 2 次提交
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由 James Bottomley 提交于
Currently, get_user_pages() returns fully coherent pages to the kernel for anything other than anonymous pages. This is a problem for things like fuse and the SCSI generic ioctl SG_IO which can potentially wish to do DMA to anonymous pages passed in by users. The fix is to add a new memory management API: flush_anon_page() which is used in get_user_pages() to make anonymous pages coherent. Signed-off-by: NJames Bottomley <James.Bottomley@SteelEye.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Eric Sesterhenn 提交于
this changes if() BUG(); constructs to BUG_ON() which is cleaner, contains unlikely() and can better optimized away. Signed-off-by: NEric Sesterhenn <snakebyte@gmx.de> Signed-off-by: NAdrian Bunk <bunk@stusta.de>
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- 26 3月, 2006 1 次提交
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由 Nick Piggin 提交于
Hugh is rightly concerned that the CONFIG_DEBUG_VM coverage has gone too far in vm_normal_page, considering that we expect production kernels to be shipped with the option turned off, and that the code has been under some large changes recently. Signed-off-by: NNick Piggin <npiggin@suse.de> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 22 3月, 2006 4 次提交
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由 David Gibson 提交于
Turns out the hugepage logic in free_pgtables() was doubly broken. The loop coalescing multiple normal page VMAs into one call to free_pgd_range() had an off by one error, which could mean it would coalesce one hugepage VMA into the same bundle (checking 'vma' not 'next' in the loop). I transferred this bug into the new is_vm_hugetlb_page() based version. Here's the fix. This one didn't bite on powerpc previously for the same reason the is_hugepage_only_range() problem didn't: powerpc's hugetlb_free_pgd_range() is identical to free_pgd_range(). It didn't bite on ia64 because the hugepage region is distant enough from any other region that the separated PMD_SIZE distance test would always prevent coalescing the two together. No libhugetlbfs testsuite regressions (ppc64, POWER5). Signed-off-by: NDavid Gibson <dwg@au1.ibm.com> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 David Gibson 提交于
free_pgtables() has special logic to call hugetlb_free_pgd_range() instead of the normal free_pgd_range() on hugepage VMAs. However, the test it uses to do so is incorrect: it calls is_hugepage_only_range on a hugepage sized range at the start of the vma. is_hugepage_only_range() will return true if the given range has any intersection with a hugepage address region, and in this case the given region need not be hugepage aligned. So, for example, this test can return true if called on, say, a 4k VMA immediately preceding a (nicely aligned) hugepage VMA. At present we get away with this because the powerpc version of hugetlb_free_pgd_range() is just a call to free_pgd_range(). On ia64 (the only other arch with a non-trivial is_hugepage_only_range()) we get away with it for a different reason; the hugepage area is not contiguous with the rest of the user address space, and VMAs are not permitted in between, so the test can't return a false positive there. Nonetheless this should be fixed. We do that in the patch below by replacing the is_hugepage_only_range() test with an explicit test of the VMA using is_vm_hugetlb_page(). This in turn changes behaviour for platforms where is_hugepage_only_range() returns false always (everything except powerpc and ia64). We address this by ensuring that hugetlb_free_pgd_range() is defined to be identical to free_pgd_range() (instead of a no-op) on everything except ia64. Even so, it will prevent some otherwise possible coalescing of calls down to free_pgd_range(). Since this only happens for hugepage VMAs, removing this small optimization seems unlikely to cause any trouble. This patch causes no regressions on the libhugetlbfs testsuite - ppc64 POWER5 (8-way), ppc64 G5 (2-way) and i386 Pentium M (UP). Signed-off-by: NDavid Gibson <dwg@au1.ibm.com> Cc: William Lee Irwin III <wli@holomorphy.com> Acked-by: NHugh Dickins <hugh@veritas.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Nick Piggin 提交于
Put a few more checks under CONFIG_DEBUG_VM Signed-off-by: NNick Piggin <npiggin@suse.de> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Nick Piggin 提交于
Have an explicit mm call to split higher order pages into individual pages. Should help to avoid bugs and be more explicit about the code's intention. Signed-off-by: NNick Piggin <npiggin@suse.de> Cc: Russell King <rmk@arm.linux.org.uk> Cc: David Howells <dhowells@redhat.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mundt <lethal@linux-sh.org> Cc: "David S. Miller" <davem@davemloft.net> Cc: Chris Zankel <chris@zankel.net> Signed-off-by: NYoichi Yuasa <yoichi_yuasa@tripeaks.co.jp> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 17 3月, 2006 1 次提交
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由 Hugh Dickins 提交于
Lee Revell reported 28ms latency when process with lots of swapped memory exits. 2.6.15 introduced a latency regression when unmapping: in accounting the zap_work latency breaker, pte_none counted 1, pte_present PAGE_SIZE, but a swap entry counted nothing at all. We think of pages present as the slow case, but Lee's trace shows that free_swap_and_cache's radix tree lookup can make a lot of work - and we could have been doing it many thousands of times without a latency break. Move the zap_work update up to account swap entries like pages present. This does account non-linear pte_file entries, and unmap_mapping_range skipping over swap entries, by the same amount even though they're quick: but neither of those cases deserves complicating the code (and they're treated no worse than they were in 2.6.14). Signed-off-by: NHugh Dickins <hugh@veritas.com> Acked-by: NNick Piggin <npiggin@suse.de> Acked-by: NIngo Molnar <mingo@elte.hu> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 18 2月, 2006 1 次提交
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由 Andi Kleen 提交于
AMD SimNow!'s JIT doesn't like them at all in the guest. For distribution installation it's easiest if it's a boot time option. Also I moved the variable to a more appropiate place and make it independent from sysctl And marked __read_mostly which it is. Signed-off-by: NAndi Kleen <ak@suse.de> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 02 2月, 2006 1 次提交
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由 Christoph Lameter 提交于
Check for PageSwapCache after looking up and locking a swap page. The page migration code may change a swap pte to point to a different page under lock_page(). If that happens then the vm must retry the lookup operation in the swap space to find the correct page number. There are a couple of locations in the VM where a lock_page() is done on a swap page. In these locations we need to check afterwards if the page was migrated. If the page was migrated then the old page that was looked up before was freed and no longer has the PageSwapCache bit set. Signed-off-by: NHirokazu Takahashi <taka@valinux.co.jp> Signed-off-by: NDave Hansen <haveblue@us.ibm.com> Signed-off-by: Christoph Lameter <clameter@@sgi.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 10 1月, 2006 1 次提交
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由 Jes Sorensen 提交于
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: NIngo Molnar <mingo@elte.hu> (finished the conversion) Signed-off-by: NJes Sorensen <jes@sgi.com> Signed-off-by: NIngo Molnar <mingo@elte.hu>
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- 09 1月, 2006 1 次提交
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由 Arnd Bergmann 提交于
This is the current version of the spu file system, used for driving SPEs on the Cell Broadband Engine. This release is almost identical to the version for the 2.6.14 kernel posted earlier, which is available as part of the Cell BE Linux distribution from http://www.bsc.es/projects/deepcomputing/linuxoncell/. The first patch provides all the interfaces for running spu application, but does not have any support for debugging SPU tasks or for scheduling. Both these functionalities are added in the subsequent patches. See Documentation/filesystems/spufs.txt on how to use spufs. Signed-off-by: NArnd Bergmann <arndb@de.ibm.com> Signed-off-by: NPaul Mackerras <paulus@samba.org>
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- 07 1月, 2006 3 次提交
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由 Nick Piggin 提交于
This atomic operation is superfluous: the pte will be added with the referenced bit set, and the page will be referenced through this mapping after the page fault handler returns anyway. Signed-off-by: NNick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Nick Piggin 提交于
Optimise rmap functions by minimising atomic operations when we know there will be no concurrent modifications. Signed-off-by: NNick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Badari Pulavarty 提交于
Here is the patch to implement madvise(MADV_REMOVE) - which frees up a given range of pages & its associated backing store. Current implementation supports only shmfs/tmpfs and other filesystems return -ENOSYS. "Some app allocates large tmpfs files, then when some task quits and some client disconnect, some memory can be released. However the only way to release tmpfs-swap is to MADV_REMOVE". - Andrea Arcangeli Databases want to use this feature to drop a section of their bufferpool (shared memory segments) - without writing back to disk/swap space. This feature is also useful for supporting hot-plug memory on UML. Concerns raised by Andrew Morton: - "We have no plan for holepunching! If we _do_ have such a plan (or might in the future) then what would the API look like? I think sys_holepunch(fd, start, len), so we should start out with that." - Using madvise is very weird, because people will ask "why do I need to mmap my file before I can stick a hole in it?" - None of the other madvise operations call into the filesystem in this manner. A broad question is: is this capability an MM operation or a filesytem operation? truncate, for example, is a filesystem operation which sometimes has MM side-effects. madvise is an mm operation and with this patch, it gains FS side-effects, only they're really, really significant ones." Comments: - Andrea suggested the fs operation too but then it's more efficient to have it as a mm operation with fs side effects, because they don't immediatly know fd and physical offset of the range. It's possible to fixup in userland and to use the fs operation but it's more expensive, the vmas are already in the kernel and we can use them. Short term plan & Future Direction: - We seem to need this interface only for shmfs/tmpfs files in the short term. We have to add hooks into the filesystem for correctness and completeness. This is what this patch does. - In the future, plan is to support both fs and mmap apis also. This also involves (other) filesystem specific functions to be implemented. - Current patch doesn't support VM_NONLINEAR - which can be addressed in the future. Signed-off-by: NBadari Pulavarty <pbadari@us.ibm.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Andrea Arcangeli <andrea@suse.de> Cc: Michael Kerrisk <mtk-manpages@gmx.net> Cc: Ulrich Drepper <drepper@redhat.com> Signed-off-by: NAndrew Morton <akpm@osdl.org> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 17 12月, 2005 1 次提交
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由 Linus Torvalds 提交于
The logic that decides that a fork() might be able to avoid copying a VM area when it can be re-created by page faults didn't know about the new vm_insert_page() case. Also make some things a bit more anal wrt VM_PFNMAP. Pointed out by Hugh Dickins <hugh@veritas.com> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 13 12月, 2005 1 次提交
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由 Linus Torvalds 提交于
Nick Piggin points out that a few drivers play games with VM_IO (why? who knows..) and thus a pfn-remapped area may not have that bit set even if remap_pfn_range() set it originally. So make it explicit in get_user_pages() that we don't follow VM_PFNMAP pages, since pretty much by definition they do not have a "struct page" associated with them. Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 12 12月, 2005 3 次提交
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由 Linus Torvalds 提交于
The VM layer (for historical reasons) turns a read-only shared mmap into a private-like mapping with the VM_MAYWRITE bit clear. Thus checking just VM_SHARED isn't actually sufficient. So use a trivial helper function for the cases where we wanted to inquire if a mapping was COW-like or not. Moo! Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Linus Torvalds 提交于
With the previous commit, we can handle arbitrary shared re-mappings even without this complexity, and since the only known private mappings are for strange users of /dev/mem (which never create an incomplete one), there seems to be no reason to support it. Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Linus Torvalds 提交于
A shared mapping doesn't cause COW-pages, so we don't need to worry about the whole vm_pgoff logic to decide if a PFN-remapped page has gone through COW or not. This makes it possible to entirely avoid the special "partial remapping" logic for the common case. Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 04 12月, 2005 1 次提交
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由 Linus Torvalds 提交于
It used to use remap_pfn_range(), which wasn't GPL-only either, and the new interface is actually simpler and does more checking, so we shouldn't unnecessarily discourage people from switching over. Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 01 12月, 2005 1 次提交
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由 Linus Torvalds 提交于
This is what a lot of drivers will actually want to use to insert individual pages into a user VMA. It doesn't have the old PageReserved restrictions of remap_pfn_range(), and it doesn't complain about partial remappings. The page you insert needs to be a nice clean kernel allocation, so you can't insert arbitrary page mappings with this, but that's not what people want. Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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- 30 11月, 2005 4 次提交
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由 Trond Myklebust 提交于
Signed-off-by: NTrond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Hugh Dickins 提交于
Use copy_user_highpage directly instead of cow_user_page in do_no_page: in the immediately following page_cache_release, and elsewhere, it is assuming that new_page is normal. If any VM_PFNMAP driver can get to do_no_page, it's just a BUG (but not in the case of do_anonymous_page). Signed-off-by: NHugh Dickins <hugh@veritas.com> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Hugh Dickins 提交于
Clean away do_wp_page's "src_page": cow_user_page makes it unnecessary. Signed-off-by: NHugh Dickins <hugh@veritas.com> Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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由 Linus Torvalds 提交于
High Dickins points out that the user virtual address passed to the page fault handler isn't necessarily page-aligned. Also, add a comment on why the copy could fail for the user address case. Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
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