Date: Fri, 15 Nov 2013 16:35:29 +0000 (UTC) From: "Justin T. Gibbs" <gibbs@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r258178 - head/sys/dev/xen/balloon Message-ID: <201311151635.rAFGZTv1086190@svn.freebsd.org>
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Author: gibbs Date: Fri Nov 15 16:35:28 2013 New Revision: 258178 URL: http://svnweb.freebsd.org/changeset/base/258178 Log: Improve robustness of the Xen balloon driver. sys/dev/xen/balloon/balloon.c: Remove unused and commented out code. Fix deadlock caused by performing a sleepable malloc while holding the balloon mutex. Perform proper accounting of the memory used by the domain. Submitted by: Roger Pau Monné Sponsored by: Citrix Systems R&D Reviewed by: gibbs MFC after: 2 days Modified: head/sys/dev/xen/balloon/balloon.c Modified: head/sys/dev/xen/balloon/balloon.c ============================================================================== --- head/sys/dev/xen/balloon/balloon.c Fri Nov 15 16:16:55 2013 (r258177) +++ head/sys/dev/xen/balloon/balloon.c Fri Nov 15 16:35:28 2013 (r258178) @@ -52,18 +52,13 @@ __FBSDID("$FreeBSD$"); static MALLOC_DEFINE(M_BALLOON, "Balloon", "Xen Balloon Driver"); -struct mtx balloon_mutex; +/* Convert from KB (as fetched from xenstore) to number of PAGES */ +#define KB_TO_PAGE_SHIFT (PAGE_SHIFT - 10) -/* - * Protects atomic reservation decrease/increase against concurrent increases. - * Also protects non-atomic updates of current_pages and driver_pages, and - * balloon lists. - */ -struct mtx balloon_lock; +struct mtx balloon_mutex; /* We increase/decrease in batches which fit in a page */ static unsigned long frame_list[PAGE_SIZE / sizeof(unsigned long)]; -#define ARRAY_SIZE(A) (sizeof(A) / sizeof(A[0])) struct balloon_stats { /* We aim for 'current allocation' == 'target allocation'. */ @@ -116,15 +111,21 @@ static void balloon_process(void *unused printk(KERN_WARNING "xen_mem: " fmt, ##args) /* balloon_append: add the given page to the balloon. */ -static void +static int balloon_append(vm_page_t page) { struct balloon_entry *entry; - entry = malloc(sizeof(struct balloon_entry), M_BALLOON, M_WAITOK); + mtx_assert(&balloon_mutex, MA_OWNED); + + entry = malloc(sizeof(struct balloon_entry), M_BALLOON, M_NOWAIT); + if (!entry) + return (ENOMEM); entry->page = page; STAILQ_INSERT_HEAD(&ballooned_pages, entry, list); bs.balloon_low++; + + return (0); } /* balloon_retrieve: rescue a page from the balloon, if it is not empty. */ @@ -134,8 +135,10 @@ balloon_retrieve(void) vm_page_t page; struct balloon_entry *entry; + mtx_assert(&balloon_mutex, MA_OWNED); + if (STAILQ_EMPTY(&ballooned_pages)) - return NULL; + return (NULL); entry = STAILQ_FIRST(&ballooned_pages); STAILQ_REMOVE_HEAD(&ballooned_pages, list); @@ -145,7 +148,7 @@ balloon_retrieve(void) bs.balloon_low--; - return page; + return (page); } static unsigned long @@ -154,21 +157,22 @@ current_target(void) unsigned long target = min(bs.target_pages, bs.hard_limit); if (target > (bs.current_pages + bs.balloon_low + bs.balloon_high)) target = bs.current_pages + bs.balloon_low + bs.balloon_high; - return target; + return (target); } static unsigned long minimum_target(void) { #ifdef XENHVM -#define max_pfn physmem +#define max_pfn realmem #else #define max_pfn HYPERVISOR_shared_info->arch.max_pfn #endif unsigned long min_pages, curr_pages = current_target(); #define MB2PAGES(mb) ((mb) << (20 - PAGE_SHIFT)) - /* Simple continuous piecewiese linear function: + /* + * Simple continuous piecewiese linear function: * max MiB -> min MiB gradient * 0 0 * 16 16 @@ -189,12 +193,10 @@ minimum_target(void) else min_pages = MB2PAGES(296) + (max_pfn >> 5); #undef MB2PAGES +#undef max_pfn /* Don't enforce growth */ - return min(min_pages, curr_pages); -#ifndef CONFIG_XEN -#undef max_pfn -#endif + return (min(min_pages, curr_pages)); } static int @@ -210,10 +212,10 @@ increase_reservation(unsigned long nr_pa .domid = DOMID_SELF }; - if (nr_pages > ARRAY_SIZE(frame_list)) - nr_pages = ARRAY_SIZE(frame_list); + mtx_assert(&balloon_mutex, MA_OWNED); - mtx_lock(&balloon_lock); + if (nr_pages > nitems(frame_list)) + nr_pages = nitems(frame_list); for (entry = STAILQ_FIRST(&ballooned_pages), i = 0; i < nr_pages; i++, entry = STAILQ_NEXT(entry, list)) { @@ -253,33 +255,14 @@ increase_reservation(unsigned long nr_pa set_phys_to_machine(pfn, frame_list[i]); -#if 0 -#ifndef XENHVM - /* Link back into the page tables if not highmem. */ - if (pfn < max_low_pfn) { - int ret; - ret = HYPERVISOR_update_va_mapping( - (unsigned long)__va(pfn << PAGE_SHIFT), - pfn_pte_ma(frame_list[i], PAGE_KERNEL), - 0); - PASSING(ret == 0, - ("HYPERVISOR_update_va_mapping failed")); - } -#endif -#endif - - /* Relinquish the page back to the allocator. */ vm_page_unwire(page, 0); vm_page_free(page); } bs.current_pages += nr_pages; - //totalram_pages = bs.current_pages; out: - mtx_unlock(&balloon_lock); - - return 0; + return (0); } static int @@ -295,8 +278,10 @@ decrease_reservation(unsigned long nr_pa .domid = DOMID_SELF }; - if (nr_pages > ARRAY_SIZE(frame_list)) - nr_pages = ARRAY_SIZE(frame_list); + mtx_assert(&balloon_mutex, MA_OWNED); + + if (nr_pages > nitems(frame_list)) + nr_pages = nitems(frame_list); for (i = 0; i < nr_pages; i++) { if ((page = vm_page_alloc(NULL, 0, @@ -310,39 +295,15 @@ decrease_reservation(unsigned long nr_pa pfn = (VM_PAGE_TO_PHYS(page) >> PAGE_SHIFT); frame_list[i] = PFNTOMFN(pfn); -#if 0 - if (!PageHighMem(page)) { - v = phys_to_virt(pfn << PAGE_SHIFT); - scrub_pages(v, 1); -#ifdef CONFIG_XEN - ret = HYPERVISOR_update_va_mapping( - (unsigned long)v, __pte_ma(0), 0); - BUG_ON(ret); -#endif - } -#endif -#ifdef CONFIG_XEN_SCRUB_PAGES - else { - v = kmap(page); - scrub_pages(v, 1); - kunmap(page); - } -#endif - } - -#ifdef CONFIG_XEN - /* Ensure that ballooned highmem pages don't have kmaps. */ - kmap_flush_unused(); - flush_tlb_all(); -#endif - - mtx_lock(&balloon_lock); - - /* No more mappings: invalidate P2M and add to balloon. */ - for (i = 0; i < nr_pages; i++) { - pfn = MFNTOPFN(frame_list[i]); set_phys_to_machine(pfn, INVALID_P2M_ENTRY); - balloon_append(PHYS_TO_VM_PAGE(pfn << PAGE_SHIFT)); + if (balloon_append(page) != 0) { + vm_page_unwire(page, 0); + vm_page_free(page); + + nr_pages = i; + need_sleep = 1; + break; + } } set_xen_guest_handle(reservation.extent_start, frame_list); @@ -351,9 +312,6 @@ decrease_reservation(unsigned long nr_pa KASSERT(ret == nr_pages, ("HYPERVISOR_memory_op failed")); bs.current_pages -= nr_pages; - //totalram_pages = bs.current_pages; - - mtx_unlock(&balloon_lock); return (need_sleep); } @@ -425,11 +383,11 @@ watch_target(struct xs_watch *watch, return; } - /* The given memory/target value is in KiB, so it needs converting to - pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10. - */ - set_new_target(new_target >> (PAGE_SHIFT - 10)); - + /* + * The given memory/target value is in KiB, so it needs converting to + * pages. PAGE_SHIFT converts bytes to pages, hence PAGE_SHIFT - 10. + */ + set_new_target(new_target >> KB_TO_PAGE_SHIFT); } static void @@ -461,13 +419,12 @@ balloon_init(void *arg) if (!is_running_on_xen()) return; - mtx_init(&balloon_lock, "balloon_lock", NULL, MTX_DEF); mtx_init(&balloon_mutex, "balloon_mutex", NULL, MTX_DEF); #ifndef XENHVM bs.current_pages = min(xen_start_info->nr_pages, max_pfn); #else - bs.current_pages = physmem; + bs.current_pages = realmem; #endif bs.target_pages = bs.current_pages; bs.balloon_low = 0; @@ -497,76 +454,7 @@ void balloon_update_driver_allowance(lon void balloon_update_driver_allowance(long delta) { - mtx_lock(&balloon_lock); + mtx_lock(&balloon_mutex); bs.driver_pages += delta; - mtx_unlock(&balloon_lock); -} - -#if 0 -static int dealloc_pte_fn( - pte_t *pte, struct page *pte_page, unsigned long addr, void *data) -{ - unsigned long mfn = pte_mfn(*pte); - int ret; - struct xen_memory_reservation reservation = { - .extent_start = &mfn, - .nr_extents = 1, - .extent_order = 0, - .domid = DOMID_SELF - }; - set_pte_at(&init_mm, addr, pte, __pte_ma(0)); - set_phys_to_machine(__pa(addr) >> PAGE_SHIFT, INVALID_P2M_ENTRY); - ret = HYPERVISOR_memory_op(XENMEM_decrease_reservation, &reservation); - KASSERT(ret == 1, ("HYPERVISOR_memory_op failed")); - return 0; -} - -#endif - -#if 0 -vm_page_t -balloon_alloc_empty_page_range(unsigned long nr_pages) -{ - vm_page_t pages; - int i, rc; - unsigned long *mfn_list; - struct xen_memory_reservation reservation = { - .address_bits = 0, - .extent_order = 0, - .domid = DOMID_SELF - }; - - pages = vm_page_alloc_contig(nr_pages, 0, -1, 4, 4) - if (pages == NULL) - return NULL; - - mfn_list = malloc(nr_pages*sizeof(unsigned long), M_DEVBUF, M_WAITOK); - - for (i = 0; i < nr_pages; i++) { - mfn_list[i] = PFNTOMFN(VM_PAGE_TO_PHYS(pages[i]) >> PAGE_SHIFT); - PFNTOMFN(i) = INVALID_P2M_ENTRY; - reservation.extent_start = mfn_list; - reservation.nr_extents = nr_pages; - rc = HYPERVISOR_memory_op(XENMEM_decrease_reservation, - &reservation); - KASSERT(rc == nr_pages, ("HYPERVISOR_memory_op failed")); - } - - current_pages -= nr_pages; - - wakeup(balloon_process); - - return pages; -} - -void -balloon_dealloc_empty_page_range(vm_page_t page, unsigned long nr_pages) -{ - unsigned long i; - - for (i = 0; i < nr_pages; i++) - balloon_append(page + i); - - wakeup(balloon_process); + mtx_unlock(&balloon_mutex); } -#endif
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