From 1ef2f06b71792c2efaa4fb4aef8f1fc2a115ee1f Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Thu, 31 Oct 2019 15:29:28 +0100 Subject: [PATCH] powerpc/pseries/cmm: Convert loaned_pages to an atomic_long_t When switching to balloon compaction, we want to drop the cmm_lock and completely rely on the balloon compaction list lock internally. loaned_pages is currently protected under the cmm_lock. Note: Right now cmm_alloc_pages() and cmm_free_pages() can be called at the same time, e.g., via the thread and a concurrent OOM notifier. Signed-off-by: David Hildenbrand Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20191031142933.10779-8-david@redhat.com --- arch/powerpc/platforms/pseries/cmm.c | 35 +++++++++++++++------------- 1 file changed, 19 insertions(+), 16 deletions(-) diff --git a/arch/powerpc/platforms/pseries/cmm.c b/arch/powerpc/platforms/pseries/cmm.c index 29416b621189..3a55dd1fdd39 100644 --- a/arch/powerpc/platforms/pseries/cmm.c +++ b/arch/powerpc/platforms/pseries/cmm.c @@ -73,7 +73,7 @@ MODULE_PARM_DESC(debug, "Enable module debugging logging. Set to 1 to enable. " #define cmm_dbg(...) if (cmm_debug) { printk(KERN_INFO "cmm: "__VA_ARGS__); } -static unsigned long loaned_pages; +static atomic_long_t loaned_pages; static unsigned long loaned_pages_target; static unsigned long oom_freed_pages; @@ -159,7 +159,7 @@ static long cmm_alloc_pages(long nr) } list_add(&page->lru, &cmm_page_list); - loaned_pages++; + atomic_long_inc(&loaned_pages); adjust_managed_page_count(page, -1); spin_unlock(&cmm_lock); nr--; @@ -189,7 +189,7 @@ static long cmm_free_pages(long nr) list_del(&page->lru); adjust_managed_page_count(page, 1); __free_page(page); - loaned_pages--; + atomic_long_dec(&loaned_pages); nr--; } spin_unlock(&cmm_lock); @@ -214,7 +214,7 @@ static int cmm_oom_notify(struct notifier_block *self, cmm_dbg("OOM processing started\n"); nr = cmm_free_pages(nr); - loaned_pages_target = loaned_pages; + loaned_pages_target = atomic_long_read(&loaned_pages); *freed += KB2PAGES(oom_kb) - nr; oom_freed_pages += KB2PAGES(oom_kb) - nr; cmm_dbg("OOM processing complete\n"); @@ -231,10 +231,11 @@ static int cmm_oom_notify(struct notifier_block *self, **/ static void cmm_get_mpp(void) { + const long __loaned_pages = atomic_long_read(&loaned_pages); + const long total_pages = totalram_pages() + __loaned_pages; int rc; struct hvcall_mpp_data mpp_data; signed long active_pages_target, page_loan_request, target; - signed long total_pages = totalram_pages() + loaned_pages; signed long min_mem_pages = (min_mem_mb * 1024 * 1024) / PAGE_SIZE; rc = h_get_mpp(&mpp_data); @@ -243,7 +244,7 @@ static void cmm_get_mpp(void) return; page_loan_request = div_s64((s64)mpp_data.loan_request, PAGE_SIZE); - target = page_loan_request + (signed long)loaned_pages; + target = page_loan_request + __loaned_pages; if (target < 0 || total_pages < min_mem_pages) target = 0; @@ -264,7 +265,7 @@ static void cmm_get_mpp(void) loaned_pages_target = target; cmm_dbg("delta = %ld, loaned = %lu, target = %lu, oom = %lu, totalram = %lu\n", - page_loan_request, loaned_pages, loaned_pages_target, + page_loan_request, __loaned_pages, loaned_pages_target, oom_freed_pages, totalram_pages()); } @@ -282,6 +283,7 @@ static struct notifier_block cmm_oom_nb = { static int cmm_thread(void *dummy) { unsigned long timeleft; + long __loaned_pages; while (1) { timeleft = msleep_interruptible(delay * 1000); @@ -312,11 +314,12 @@ static int cmm_thread(void *dummy) cmm_get_mpp(); - if (loaned_pages_target > loaned_pages) { - if (cmm_alloc_pages(loaned_pages_target - loaned_pages)) - loaned_pages_target = loaned_pages; - } else if (loaned_pages_target < loaned_pages) - cmm_free_pages(loaned_pages - loaned_pages_target); + __loaned_pages = atomic_long_read(&loaned_pages); + if (loaned_pages_target > __loaned_pages) { + if (cmm_alloc_pages(loaned_pages_target - __loaned_pages)) + loaned_pages_target = __loaned_pages; + } else if (loaned_pages_target < __loaned_pages) + cmm_free_pages(__loaned_pages - loaned_pages_target); } return 0; } @@ -330,7 +333,7 @@ static int cmm_thread(void *dummy) } \ static DEVICE_ATTR(name, 0444, show_##name, NULL) -CMM_SHOW(loaned_kb, "%lu\n", PAGES2KB(loaned_pages)); +CMM_SHOW(loaned_kb, "%lu\n", PAGES2KB(atomic_long_read(&loaned_pages))); CMM_SHOW(loaned_target_kb, "%lu\n", PAGES2KB(loaned_pages_target)); static ssize_t show_oom_pages(struct device *dev, @@ -433,7 +436,7 @@ static int cmm_reboot_notifier(struct notifier_block *nb, if (cmm_thread_ptr) kthread_stop(cmm_thread_ptr); cmm_thread_ptr = NULL; - cmm_free_pages(loaned_pages); + cmm_free_pages(atomic_long_read(&loaned_pages)); } return NOTIFY_DONE; } @@ -540,7 +543,7 @@ static void cmm_exit(void) unregister_oom_notifier(&cmm_oom_nb); unregister_reboot_notifier(&cmm_reboot_nb); unregister_memory_notifier(&cmm_mem_nb); - cmm_free_pages(loaned_pages); + cmm_free_pages(atomic_long_read(&loaned_pages)); cmm_unregister_sysfs(&cmm_dev); } @@ -561,7 +564,7 @@ static int cmm_set_disable(const char *val, const struct kernel_param *kp) if (cmm_thread_ptr) kthread_stop(cmm_thread_ptr); cmm_thread_ptr = NULL; - cmm_free_pages(loaned_pages); + cmm_free_pages(atomic_long_read(&loaned_pages)); } else if (!disable && cmm_disabled) { cmm_thread_ptr = kthread_run(cmm_thread, NULL, "cmmthread"); if (IS_ERR(cmm_thread_ptr)) -- 2.30.2