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[RE-RESEND PATCH 1/4] usb: musb: Fix runtime PM race in musb_queue_resume_work

by Paul Cercueil

musb_queue_resume_work() would call the provided callback if the runtime PM status was 'active'. Otherwise, it would enqueue the request if the hardware was still suspended (musb->is_runtime_suspended is true). This causes a race with the runtime PM handlers, as it is possible to be in the case where the runtime PM status is not yet 'active', but the hardware has been awaken (PM resume function has been called). When hitting the race, the resume work was not enqueued, which probably triggered other bugs further down the stack. For instance, a telnet connection on Ingenic SoCs would result in a 50/50 chance of a segmentation fault somewhere in the musb code. Rework the code so that either we call the callback directly if (musb->is_runtime_suspended == 0), or enqueue the query otherwise. Fixes: ea2f35c01d5e ("usb: musb: Fix sleeping function called from invalid context for hdrc glue") Cc: stable(a)vger.kernel.org # v4.9+ Signed-off-by: Paul Cercueil <paul(a)crapouillou.net> Reviewed-by: Tony Lindgren <tony(a)atomide.com> Tested-by: Tony Lindgren <tony(a)atomide.com> --- drivers/usb/musb/musb_core.c | 31 +++++++++++++++++-------------- 1 file changed, 17 insertions(+), 14 deletions(-) diff --git a/drivers/usb/musb/musb_core.c b/drivers/usb/musb/musb_core.c index 849e0b770130..1cd87729ba60 100644 --- a/drivers/usb/musb/musb_core.c +++ b/drivers/usb/musb/musb_core.c @@ -2240,32 +2240,35 @@ int musb_queue_resume_work(struct musb *musb, { struct musb_pending_work *w; unsigned long flags; + bool is_suspended; int error; if (WARN_ON(!callback)) return -EINVAL; - if (pm_runtime_active(musb->controller)) - return callback(musb, data); + spin_lock_irqsave(&musb->list_lock, flags); + is_suspended = musb->is_runtime_suspended; + + if (is_suspended) { + w = devm_kzalloc(musb->controller, sizeof(*w), GFP_ATOMIC); + if (!w) { + error = -ENOMEM; + goto out_unlock; + } - w = devm_kzalloc(musb->controller, sizeof(*w), GFP_ATOMIC); - if (!w) - return -ENOMEM; + w->callback = callback; + w->data = data; - w->callback = callback; - w->data = data; - spin_lock_irqsave(&musb->list_lock, flags); - if (musb->is_runtime_suspended) { list_add_tail(&w->node, &musb->pending_list); error = 0; - } else { - dev_err(musb->controller, "could not add resume work %p\n", - callback); - devm_kfree(musb->controller, w); - error = -EINPROGRESS; } + +out_unlock: spin_unlock_irqrestore(&musb->list_lock, flags); + if (!is_suspended) + error = callback(musb, data); + return error; } EXPORT_SYMBOL_GPL(musb_queue_resume_work); -- 2.29.2

4 years, 6 months

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[patch 18/19] proc_sysctl: fix oops caused by incorrect command parameters

by Andrew Morton

From: Xiaoming Ni <nixiaoming(a)huawei.com> Subject: proc_sysctl: fix oops caused by incorrect command parameters The process_sysctl_arg() does not check whether val is empty before invoking strlen(val). If the command line parameter () is incorrectly configured and val is empty, oops is triggered. For example: "hung_task_panic=1" is incorrectly written as "hung_task_panic", oops is triggered. The call stack is as follows: Kernel command line: .... hung_task_panic ...... Call trace: __pi_strlen+0x10/0x98 parse_args+0x278/0x344 do_sysctl_args+0x8c/0xfc kernel_init+0x5c/0xf4 ret_from_fork+0x10/0x30 To fix it, check whether "val" is empty when "phram" is a sysctl field. Error codes are returned in the failure branch, and error logs are generated by parse_args(). Link: https://lkml.kernel.org/r/20210118133029.28580-1-nixiaoming@huawei.com Fixes: 3db978d480e2843 ("kernel/sysctl: support setting sysctl parameters from kernel command line") Signed-off-by: Xiaoming Ni <nixiaoming(a)huawei.com> Acked-by: Vlastimil Babka <vbabka(a)suse.cz> Cc: Luis Chamberlain <mcgrof(a)kernel.org> Cc: Kees Cook <keescook(a)chromium.org> Cc: Iurii Zaikin <yzaikin(a)google.com> Cc: Alexey Dobriyan <adobriyan(a)gmail.com> Cc: Michal Hocko <mhocko(a)suse.com> Cc: Masami Hiramatsu <mhiramat(a)kernel.org> Cc: Heiner Kallweit <hkallweit1(a)gmail.com> Cc: Randy Dunlap <rdunlap(a)infradead.org> Cc: <stable(a)vger.kernel.org> [5.8+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- fs/proc/proc_sysctl.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/fs/proc/proc_sysctl.c~proc_sysctl-fix-oops-caused-by-incorrect-command-parameters +++ a/fs/proc/proc_sysctl.c @@ -1770,6 +1770,12 @@ static int process_sysctl_arg(char *para return 0; } + if (!val) + return -EINVAL; + len = strlen(val); + if (len == 0) + return -EINVAL; + /* * To set sysctl options, we use a temporary mount of proc, look up the * respective sys/ file and write to it. To avoid mounting it when no @@ -1811,7 +1817,6 @@ static int process_sysctl_arg(char *para file, param, val); goto out; } - len = strlen(val); wret = kernel_write(file, val, len, &pos); if (wret < 0) { err = wret; _

4 years, 6 months

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[patch 13/19] mm: fix page reference leak in soft_offline_page()

by Andrew Morton

From: Dan Williams <dan.j.williams(a)intel.com> Subject: mm: fix page reference leak in soft_offline_page() The conversion to move pfn_to_online_page() internal to soft_offline_page() missed that the get_user_pages() reference taken by the madvise() path needs to be dropped when pfn_to_online_page() fails. Note the direct sysfs-path to soft_offline_page() does not perform a get_user_pages() lookup. When soft_offline_page() is handed a pfn_valid() && !pfn_to_online_page() pfn the kernel hangs at dax-device shutdown due to a leaked reference. Link: https://lkml.kernel.org/r/161058501210.1840162.8108917599181157327.stgit@dw… Fixes: feec24a6139d ("mm, soft-offline: convert parameter to pfn") Signed-off-by: Dan Williams <dan.j.williams(a)intel.com> Reviewed-by: David Hildenbrand <david(a)redhat.com> Reviewed-by: Oscar Salvador <osalvador(a)suse.de> Reviewed-by: Naoya Horiguchi <naoya.horiguchi(a)nec.com> Cc: Michal Hocko <mhocko(a)suse.com> Cc: Qian Cai <cai(a)lca.pw> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/memory-failure.c | 20 ++++++++++++++++---- 1 file changed, 16 insertions(+), 4 deletions(-) --- a/mm/memory-failure.c~mm-fix-page-reference-leak-in-soft_offline_page +++ a/mm/memory-failure.c @@ -1885,6 +1885,12 @@ static int soft_offline_free_page(struct return rc; } +static void put_ref_page(struct page *page) +{ + if (page) + put_page(page); +} + /** * soft_offline_page - Soft offline a page. * @pfn: pfn to soft-offline @@ -1910,20 +1916,26 @@ static int soft_offline_free_page(struct int soft_offline_page(unsigned long pfn, int flags) { int ret; - struct page *page; bool try_again = true; + struct page *page, *ref_page = NULL; + + WARN_ON_ONCE(!pfn_valid(pfn) && (flags & MF_COUNT_INCREASED)); if (!pfn_valid(pfn)) return -ENXIO; + if (flags & MF_COUNT_INCREASED) + ref_page = pfn_to_page(pfn); + /* Only online pages can be soft-offlined (esp., not ZONE_DEVICE). */ page = pfn_to_online_page(pfn); - if (!page) + if (!page) { + put_ref_page(ref_page); return -EIO; + } if (PageHWPoison(page)) { pr_info("%s: %#lx page already poisoned\n", __func__, pfn); - if (flags & MF_COUNT_INCREASED) - put_page(page); + put_ref_page(ref_page); return 0; } _

4 years, 6 months

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[patch 05/19] mm: fix numa stats for thp migration

by Andrew Morton

From: Shakeel Butt <shakeelb(a)google.com> Subject: mm: fix numa stats for thp migration Currently the kernel is not correctly updating the numa stats for NR_FILE_PAGES and NR_SHMEM on THP migration. Fix that. For NR_FILE_DIRTY and NR_ZONE_WRITE_PENDING, although at the moment there is no need to handle THP migration as kernel still does not have write support for file THP but to be more future proof, this patch adds the THP support for those stats as well. Link: https://lkml.kernel.org/r/20210108155813.2914586-2-shakeelb@google.com Fixes: e71769ae52609 ("mm: enable thp migration for shmem thp") Signed-off-by: Shakeel Butt <shakeelb(a)google.com> Acked-by: Yang Shi <shy828301(a)gmail.com> Reviewed-by: Roman Gushchin <guro(a)fb.com> Cc: Johannes Weiner <hannes(a)cmpxchg.org> Cc: Michal Hocko <mhocko(a)kernel.org> Cc: Muchun Song <songmuchun(a)bytedance.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/migrate.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) --- a/mm/migrate.c~mm-fix-numa-stats-for-thp-migration +++ a/mm/migrate.c @@ -402,6 +402,7 @@ int migrate_page_move_mapping(struct add struct zone *oldzone, *newzone; int dirty; int expected_count = expected_page_refs(mapping, page) + extra_count; + int nr = thp_nr_pages(page); if (!mapping) { /* Anonymous page without mapping */ @@ -437,7 +438,7 @@ int migrate_page_move_mapping(struct add */ newpage->index = page->index; newpage->mapping = page->mapping; - page_ref_add(newpage, thp_nr_pages(page)); /* add cache reference */ + page_ref_add(newpage, nr); /* add cache reference */ if (PageSwapBacked(page)) { __SetPageSwapBacked(newpage); if (PageSwapCache(page)) { @@ -459,7 +460,7 @@ int migrate_page_move_mapping(struct add if (PageTransHuge(page)) { int i; - for (i = 1; i < HPAGE_PMD_NR; i++) { + for (i = 1; i < nr; i++) { xas_next(&xas); xas_store(&xas, newpage); } @@ -470,7 +471,7 @@ int migrate_page_move_mapping(struct add * to one less reference. * We know this isn't the last reference. */ - page_ref_unfreeze(page, expected_count - thp_nr_pages(page)); + page_ref_unfreeze(page, expected_count - nr); xas_unlock(&xas); /* Leave irq disabled to prevent preemption while updating stats */ @@ -493,17 +494,17 @@ int migrate_page_move_mapping(struct add old_lruvec = mem_cgroup_lruvec(memcg, oldzone->zone_pgdat); new_lruvec = mem_cgroup_lruvec(memcg, newzone->zone_pgdat); - __dec_lruvec_state(old_lruvec, NR_FILE_PAGES); - __inc_lruvec_state(new_lruvec, NR_FILE_PAGES); + __mod_lruvec_state(old_lruvec, NR_FILE_PAGES, -nr); + __mod_lruvec_state(new_lruvec, NR_FILE_PAGES, nr); if (PageSwapBacked(page) && !PageSwapCache(page)) { - __dec_lruvec_state(old_lruvec, NR_SHMEM); - __inc_lruvec_state(new_lruvec, NR_SHMEM); + __mod_lruvec_state(old_lruvec, NR_SHMEM, -nr); + __mod_lruvec_state(new_lruvec, NR_SHMEM, nr); } if (dirty && mapping_can_writeback(mapping)) { - __dec_lruvec_state(old_lruvec, NR_FILE_DIRTY); - __dec_zone_state(oldzone, NR_ZONE_WRITE_PENDING); - __inc_lruvec_state(new_lruvec, NR_FILE_DIRTY); - __inc_zone_state(newzone, NR_ZONE_WRITE_PENDING); + __mod_lruvec_state(old_lruvec, NR_FILE_DIRTY, -nr); + __mod_zone_page_state(oldzone, NR_ZONE_WRITE_PENDING, -nr); + __mod_lruvec_state(new_lruvec, NR_FILE_DIRTY, nr); + __mod_zone_page_state(newzone, NR_ZONE_WRITE_PENDING, nr); } } local_irq_enable(); _

4 years, 6 months

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[patch 04/19] mm: memcg: fix memcg file_dirty numa stat

by Andrew Morton

From: Shakeel Butt <shakeelb(a)google.com> Subject: mm: memcg: fix memcg file_dirty numa stat The kernel updates the per-node NR_FILE_DIRTY stats on page migration but not the memcg numa stats. That was not an issue until recently the commit 5f9a4f4a7096 ("mm: memcontrol: add the missing numa_stat interface for cgroup v2") exposed numa stats for the memcg. So fix the file_dirty per-memcg numa stat. Link: https://lkml.kernel.org/r/20210108155813.2914586-1-shakeelb@google.com Fixes: 5f9a4f4a7096 ("mm: memcontrol: add the missing numa_stat interface for cgroup v2") Signed-off-by: Shakeel Butt <shakeelb(a)google.com> Reviewed-by: Muchun Song <songmuchun(a)bytedance.com> Acked-by: Yang Shi <shy828301(a)gmail.com> Reviewed-by: Roman Gushchin <guro(a)fb.com> Cc: Johannes Weiner <hannes(a)cmpxchg.org> Cc: Michal Hocko <mhocko(a)kernel.org> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/migrate.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/mm/migrate.c~mm-memcg-fix-memcg-file_dirty-numa-stat +++ a/mm/migrate.c @@ -500,9 +500,9 @@ int migrate_page_move_mapping(struct add __inc_lruvec_state(new_lruvec, NR_SHMEM); } if (dirty && mapping_can_writeback(mapping)) { - __dec_node_state(oldzone->zone_pgdat, NR_FILE_DIRTY); + __dec_lruvec_state(old_lruvec, NR_FILE_DIRTY); __dec_zone_state(oldzone, NR_ZONE_WRITE_PENDING); - __inc_node_state(newzone->zone_pgdat, NR_FILE_DIRTY); + __inc_lruvec_state(new_lruvec, NR_FILE_DIRTY); __inc_zone_state(newzone, NR_ZONE_WRITE_PENDING); } } _

4 years, 6 months

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[patch 03/19] mm: memcg/slab: optimize objcg stock draining

by Andrew Morton

From: Roman Gushchin <guro(a)fb.com> Subject: mm: memcg/slab: optimize objcg stock draining Imran Khan reported a 16% regression in hackbench results caused by the commit f2fe7b09a52b ("mm: memcg/slab: charge individual slab objects instead of pages"). The regression is noticeable in the case of a consequent allocation of several relatively large slab objects, e.g. skb's. As soon as the amount of stocked bytes exceeds PAGE_SIZE, drain_obj_stock() and __memcg_kmem_uncharge() are called, and it leads to a number of atomic operations in page_counter_uncharge(). The corresponding call graph is below (provided by Imran Khan): |__alloc_skb | | | |__kmalloc_reserve.isra.61 | | | | | |__kmalloc_node_track_caller | | | | | | | |slab_pre_alloc_hook.constprop.88 | | | obj_cgroup_charge | | | | | | | | | |__memcg_kmem_charge | | | | | | | | | | | |page_counter_try_charge | | | | | | | | | |refill_obj_stock | | | | | | | | | | | |drain_obj_stock.isra.68 | | | | | | | | | | | | | |__memcg_kmem_uncharge | | | | | | | | | | | | | | | |page_counter_uncharge | | | | | | | | | | | | | | | | | |page_counter_cancel | | | | | | | | | | | |__slab_alloc | | | | | | | | | |___slab_alloc | | | | | | | | |slab_post_alloc_hook Instead of directly uncharging the accounted kernel memory, it's possible to refill the generic page-sized per-cpu stock instead. It's a much faster operation, especially on a default hierarchy. As a bonus, __memcg_kmem_uncharge_page() will also get faster, so the freeing of page-sized kernel allocations (e.g. large kmallocs) will become faster. A similar change has been done earlier for the socket memory by the commit 475d0487a2ad ("mm: memcontrol: use per-cpu stocks for socket memory uncharging"). Link: https://lkml.kernel.org/r/20210106042239.2860107-1-guro@fb.com Fixes: f2fe7b09a52b ("mm: memcg/slab: charge individual slab objects instead of pages") Signed-off-by: Roman Gushchin <guro(a)fb.com> Reported-by: Imran Khan <imran.f.khan(a)oracle.com> Tested-by: Imran Khan <imran.f.khan(a)oracle.com> Reviewed-by: Shakeel Butt <shakeelb(a)google.com> Reviewed-by: Michal Koutn <mkoutny(a)suse.com> Cc: Michal Koutný <mkoutny(a)suse.com> Cc: Johannes Weiner <hannes(a)cmpxchg.org> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/memcontrol.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-) --- a/mm/memcontrol.c~mm-memcg-slab-optimize-objcg-stock-draining +++ a/mm/memcontrol.c @@ -3115,9 +3115,7 @@ void __memcg_kmem_uncharge(struct mem_cg if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) page_counter_uncharge(&memcg->kmem, nr_pages); - page_counter_uncharge(&memcg->memory, nr_pages); - if (do_memsw_account()) - page_counter_uncharge(&memcg->memsw, nr_pages); + refill_stock(memcg, nr_pages); } /** _

4 years, 6 months

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[patch 02/19] mm: fix initialization of struct page for holes in memory layout

by Andrew Morton

From: Mike Rapoport <rppt(a)linux.ibm.com> Subject: mm: fix initialization of struct page for holes in memory layout There could be struct pages that are not backed by actual physical memory. This can happen when the actual memory bank is not a multiple of SECTION_SIZE or when an architecture does not register memory holes reserved by the firmware as memblock.memory. Such pages are currently initialized using init_unavailable_mem() function that iterates through PFNs in holes in memblock.memory and if there is a struct page corresponding to a PFN, the fields if this page are set to default values and the page is marked as Reserved. init_unavailable_mem() does not take into account zone and node the page belongs to and sets both zone and node links in struct page to zero. On a system that has firmware reserved holes in a zone above ZONE_DMA, for instance in a configuration below: # grep -A1 E820 /proc/iomem 7a17b000-7a216fff : Unknown E820 type 7a217000-7bffffff : System RAM unset zone link in struct page will trigger VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page); because there are pages in both ZONE_DMA32 and ZONE_DMA (unset zone link in struct page) in the same pageblock. Update init_unavailable_mem() to use zone constraints defined by an architecture to properly setup the zone link and use node ID of the adjacent range in memblock.memory to set the node link. Link: https://lkml.kernel.org/r/20210111194017.22696-3-rppt@kernel.org Fixes: 73a6e474cb37 ("mm: memmap_init: iterate over memblock regions rather that check each PFN") Signed-off-by: Mike Rapoport <rppt(a)linux.ibm.com> Reported-by: Andrea Arcangeli <aarcange(a)redhat.com> Cc: Andrea Arcangeli <aarcange(a)redhat.com> Cc: Baoquan He <bhe(a)redhat.com> Cc: Borislav Petkov <bp(a)alien8.de> Cc: David Hildenbrand <david(a)redhat.com> Cc: "H. Peter Anvin" <hpa(a)zytor.com> Cc: Ingo Molnar <mingo(a)redhat.com> Cc: Mel Gorman <mgorman(a)suse.de> Cc: Michal Hocko <mhocko(a)kernel.org> Cc: Qian Cai <cai(a)lca.pw> Cc: Thomas Gleixner <tglx(a)linutronix.de> Cc: Vlastimil Babka <vbabka(a)suse.cz> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/page_alloc.c | 84 +++++++++++++++++++++++++++------------------- 1 file changed, 50 insertions(+), 34 deletions(-) --- a/mm/page_alloc.c~mm-fix-initialization-of-struct-page-for-holes-in-memory-layout +++ a/mm/page_alloc.c @@ -7078,23 +7078,26 @@ void __init free_area_init_memoryless_no * Initialize all valid struct pages in the range [spfn, epfn) and mark them * PageReserved(). Return the number of struct pages that were initialized. */ -static u64 __init init_unavailable_range(unsigned long spfn, unsigned long epfn) +static u64 __init init_unavailable_range(unsigned long spfn, unsigned long epfn, + int zone, int nid) { - unsigned long pfn; + unsigned long pfn, zone_spfn, zone_epfn; u64 pgcnt = 0; + zone_spfn = arch_zone_lowest_possible_pfn[zone]; + zone_epfn = arch_zone_highest_possible_pfn[zone]; + + spfn = clamp(spfn, zone_spfn, zone_epfn); + epfn = clamp(epfn, zone_spfn, zone_epfn); + for (pfn = spfn; pfn < epfn; pfn++) { if (!pfn_valid(ALIGN_DOWN(pfn, pageblock_nr_pages))) { pfn = ALIGN_DOWN(pfn, pageblock_nr_pages) + pageblock_nr_pages - 1; continue; } - /* - * Use a fake node/zone (0) for now. Some of these pages - * (in memblock.reserved but not in memblock.memory) will - * get re-initialized via reserve_bootmem_region() later. - */ - __init_single_page(pfn_to_page(pfn), pfn, 0, 0); + + __init_single_page(pfn_to_page(pfn), pfn, zone, nid); __SetPageReserved(pfn_to_page(pfn)); pgcnt++; } @@ -7103,51 +7106,64 @@ static u64 __init init_unavailable_range } /* - * Only struct pages that are backed by physical memory are zeroed and - * initialized by going through __init_single_page(). But, there are some - * struct pages which are reserved in memblock allocator and their fields - * may be accessed (for example page_to_pfn() on some configuration accesses - * flags). We must explicitly initialize those struct pages. + * Only struct pages that correspond to ranges defined by memblock.memory + * are zeroed and initialized by going through __init_single_page() during + * memmap_init(). * - * This function also addresses a similar issue where struct pages are left - * uninitialized because the physical address range is not covered by - * memblock.memory or memblock.reserved. That could happen when memblock - * layout is manually configured via memmap=, or when the highest physical - * address (max_pfn) does not end on a section boundary. + * But, there could be struct pages that correspond to holes in + * memblock.memory. This can happen because of the following reasons: + * - phyiscal memory bank size is not necessarily the exact multiple of the + * arbitrary section size + * - early reserved memory may not be listed in memblock.memory + * - memory layouts defined with memmap= kernel parameter may not align + * nicely with memmap sections + * + * Explicitly initialize those struct pages so that: + * - PG_Reserved is set + * - zone link is set accorging to the architecture constrains + * - node is set to node id of the next populated region except for the + * trailing hole where last node id is used */ -static void __init init_unavailable_mem(void) +static void __init init_zone_unavailable_mem(int zone) { - phys_addr_t start, end; - u64 i, pgcnt; - phys_addr_t next = 0; + unsigned long start, end; + int i, nid; + u64 pgcnt; + unsigned long next = 0; /* - * Loop through unavailable ranges not covered by memblock.memory. + * Loop through holes in memblock.memory and initialize struct + * pages corresponding to these holes */ pgcnt = 0; - for_each_mem_range(i, &start, &end) { + for_each_mem_pfn_range(i, MAX_NUMNODES, &start, &end, &nid) { if (next < start) - pgcnt += init_unavailable_range(PFN_DOWN(next), - PFN_UP(start)); + pgcnt += init_unavailable_range(next, start, zone, nid); next = end; } /* - * Early sections always have a fully populated memmap for the whole - * section - see pfn_valid(). If the last section has holes at the - * end and that section is marked "online", the memmap will be - * considered initialized. Make sure that memmap has a well defined - * state. + * Last section may surpass the actual end of memory (e.g. we can + * have 1Gb section and 512Mb of RAM pouplated). + * Make sure that memmap has a well defined state in this case. */ - pgcnt += init_unavailable_range(PFN_DOWN(next), - round_up(max_pfn, PAGES_PER_SECTION)); + end = round_up(max_pfn, PAGES_PER_SECTION); + pgcnt += init_unavailable_range(next, end, zone, nid); /* * Struct pages that do not have backing memory. This could be because * firmware is using some of this memory, or for some other reasons. */ if (pgcnt) - pr_info("Zeroed struct page in unavailable ranges: %lld pages", pgcnt); + pr_info("Zone %s: zeroed struct page in unavailable ranges: %lld pages", zone_names[zone], pgcnt); +} + +static void __init init_unavailable_mem(void) +{ + int zone; + + for (zone = 0; zone < ZONE_MOVABLE; zone++) + init_zone_unavailable_mem(zone); } #else static inline void __init init_unavailable_mem(void) _

4 years, 6 months

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[patch 01/19] x86/setup: don't remove E820_TYPE_RAM for pfn 0

by Andrew Morton

From: Mike Rapoport <rppt(a)linux.ibm.com> Subject: x86/setup: don't remove E820_TYPE_RAM for pfn 0 Patch series "mm: fix initialization of struct page for holes in memory layout", v3. Commit 73a6e474cb37 ("mm: memmap_init: iterate over memblock regions rather that check each PFN") exposed several issues with the memory map initialization and these patches fix those issues. Initially there were crashes during compaction that Qian Cai reported back in April [1]. It seemed back then that the problem was fixed, but a few weeks ago Andrea Arcangeli hit the same bug [2] and there was an additional discussion at [3]. [1] https://lore.kernel.org/lkml/8C537EB7-85EE-4DCF-943E-3CC0ED0DF56D@lca.pw [2] https://lore.kernel.org/lkml/20201121194506.13464-1-aarcange@redhat.com [3] https://lore.kernel.org/mm-commits/20201206005401.qKuAVgOXr%akpm@linux-foun… This patch (of 2): The first 4Kb of memory is a BIOS owned area and to avoid its allocation for the kernel it was not listed in e820 tables as memory. As the result, pfn 0 was never recognised by the generic memory management and it is not a part of neither node 0 nor ZONE_DMA. If set_pfnblock_flags_mask() would be ever called for the pageblock corresponding to the first 2Mbytes of memory, having pfn 0 outside of ZONE_DMA would trigger VM_BUG_ON_PAGE(!zone_spans_pfn(page_zone(page), pfn), page); Along with reserving the first 4Kb in e820 tables, several first pages are reserved with memblock in several places during setup_arch(). These reservations are enough to ensure the kernel does not touch the BIOS area and it is not necessary to remove E820_TYPE_RAM for pfn 0. Remove the update of e820 table that changes the type of pfn 0 and move the comment describing why it was done to trim_low_memory_range() that reserves the beginning of the memory. Link: https://lkml.kernel.org/r/20210111194017.22696-2-rppt@kernel.org Signed-off-by: Mike Rapoport <rppt(a)linux.ibm.com> Cc: Baoquan He <bhe(a)redhat.com> Cc: Borislav Petkov <bp(a)alien8.de> Cc: David Hildenbrand <david(a)redhat.com> Cc: "H. Peter Anvin" <hpa(a)zytor.com> Cc: Ingo Molnar <mingo(a)redhat.com> Cc: Mel Gorman <mgorman(a)suse.de> Cc: Michal Hocko <mhocko(a)kernel.org> Cc: Qian Cai <cai(a)lca.pw> Cc: Thomas Gleixner <tglx(a)linutronix.de> Cc: Vlastimil Babka <vbabka(a)suse.cz> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- arch/x86/kernel/setup.c | 20 +++++++++----------- 1 file changed, 9 insertions(+), 11 deletions(-) --- a/arch/x86/kernel/setup.c~x86-setup-dont-remove-e820_type_ram-for-pfn-0 +++ a/arch/x86/kernel/setup.c @@ -661,17 +661,6 @@ static void __init trim_platform_memory_ static void __init trim_bios_range(void) { /* - * A special case is the first 4Kb of memory; - * This is a BIOS owned area, not kernel ram, but generally - * not listed as such in the E820 table. - * - * This typically reserves additional memory (64KiB by default) - * since some BIOSes are known to corrupt low memory. See the - * Kconfig help text for X86_RESERVE_LOW. - */ - e820__range_update(0, PAGE_SIZE, E820_TYPE_RAM, E820_TYPE_RESERVED); - - /* * special case: Some BIOSes report the PC BIOS * area (640Kb -> 1Mb) as RAM even though it is not. * take them out. @@ -728,6 +717,15 @@ early_param("reservelow", parse_reservel static void __init trim_low_memory_range(void) { + /* + * A special case is the first 4Kb of memory; + * This is a BIOS owned area, not kernel ram, but generally + * not listed as such in the E820 table. + * + * This typically reserves additional memory (64KiB by default) + * since some BIOSes are known to corrupt low memory. See the + * Kconfig help text for X86_RESERVE_LOW. + */ memblock_reserve(0, ALIGN(reserve_low, PAGE_SIZE)); } _

4 years, 6 months

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+ mm-thp-fix-madv_remove-deadlock-on-shmem-thp.patch added to -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: mm: thp: fix MADV_REMOVE deadlock on shmem THP has been added to the -mm tree. Its filename is mm-thp-fix-madv_remove-deadlock-on-shmem-thp.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/mm-thp-fix-madv_remove-deadlock-o… and later at https://ozlabs.org/~akpm/mmotm/broken-out/mm-thp-fix-madv_remove-deadlock-o… Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Hugh Dickins <hughd(a)google.com> Subject: mm: thp: fix MADV_REMOVE deadlock on shmem THP Sergey reported deadlock between kswapd correctly doing its usual lock_page(page) followed by down_read(page->mapping->i_mmap_rwsem), and madvise(MADV_REMOVE) on an madvise(MADV_HUGEPAGE) area doing down_write(page->mapping->i_mmap_rwsem) followed by lock_page(page). This happened when shmem_fallocate(punch hole)'s unmap_mapping_range() reaches zap_pmd_range()'s call to __split_huge_pmd(). The same deadlock could occur when partially truncating a mapped huge tmpfs file, or using fallocate(FALLOC_FL_PUNCH_HOLE) on it. __split_huge_pmd()'s page lock was added in 5.8, to make sure that any concurrent use of reuse_swap_page() (holding page lock) could not catch the anon THP's mapcounts and swapcounts while they were being split. Fortunately, reuse_swap_page() is never applied to a shmem or file THP (not even by khugepaged, which checks PageSwapCache before calling), and anonymous THPs are never created in shmem or file areas: so that __split_huge_pmd()'s page lock can only be necessary for anonymous THPs, on which there is no risk of deadlock with i_mmap_rwsem. Link: https://lkml.kernel.org/r/alpine.LSU.2.11.2101161409470.2022@eggly.anvils Fixes: c444eb564fb1 ("mm: thp: make the THP mapcount atomic against __split_huge_pmd_locked()") Signed-off-by: Hugh Dickins <hughd(a)google.com> Reported-by: Sergey Senozhatsky <sergey.senozhatsky.work(a)gmail.com> Reviewed-by: Andrea Arcangeli <aarcange(a)redhat.com> Cc: <stable(a)vger.kernel.org> Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/huge_memory.c | 37 +++++++++++++++++++++++-------------- 1 file changed, 23 insertions(+), 14 deletions(-) --- a/mm/huge_memory.c~mm-thp-fix-madv_remove-deadlock-on-shmem-thp +++ a/mm/huge_memory.c @@ -2202,7 +2202,7 @@ void __split_huge_pmd(struct vm_area_str { spinlock_t *ptl; struct mmu_notifier_range range; - bool was_locked = false; + bool do_unlock_page = false; pmd_t _pmd; mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, vma, vma->vm_mm, @@ -2218,7 +2218,6 @@ void __split_huge_pmd(struct vm_area_str VM_BUG_ON(freeze && !page); if (page) { VM_WARN_ON_ONCE(!PageLocked(page)); - was_locked = true; if (page != pmd_page(*pmd)) goto out; } @@ -2227,19 +2226,29 @@ repeat: if (pmd_trans_huge(*pmd)) { if (!page) { page = pmd_page(*pmd); - if (unlikely(!trylock_page(page))) { - get_page(page); - _pmd = *pmd; - spin_unlock(ptl); - lock_page(page); - spin_lock(ptl); - if (unlikely(!pmd_same(*pmd, _pmd))) { - unlock_page(page); + /* + * An anonymous page must be locked, to ensure that a + * concurrent reuse_swap_page() sees stable mapcount; + * but reuse_swap_page() is not used on shmem or file, + * and page lock must not be taken when zap_pmd_range() + * calls __split_huge_pmd() while i_mmap_lock is held. + */ + if (PageAnon(page)) { + if (unlikely(!trylock_page(page))) { + get_page(page); + _pmd = *pmd; + spin_unlock(ptl); + lock_page(page); + spin_lock(ptl); + if (unlikely(!pmd_same(*pmd, _pmd))) { + unlock_page(page); + put_page(page); + page = NULL; + goto repeat; + } put_page(page); - page = NULL; - goto repeat; } - put_page(page); + do_unlock_page = true; } } if (PageMlocked(page)) @@ -2249,7 +2258,7 @@ repeat: __split_huge_pmd_locked(vma, pmd, range.start, freeze); out: spin_unlock(ptl); - if (!was_locked && page) + if (do_unlock_page) unlock_page(page); /* * No need to double call mmu_notifier->invalidate_range() callback. _ Patches currently in -mm which might be from hughd(a)google.com are mm-thp-fix-madv_remove-deadlock-on-shmem-thp.patch

4 years, 6 months

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+ revert-mm-memcontrol-avoid-workload-stalls-when-lowering-memoryhigh.patch added to -mm tree

by akpm＠linux-foundation.org

The patch titled Subject: Revert "mm: memcontrol: avoid workload stalls when lowering memory.high" has been added to the -mm tree. Its filename is revert-mm-memcontrol-avoid-workload-stalls-when-lowering-memoryhigh.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/revert-mm-memcontrol-avoid-worklo… and later at https://ozlabs.org/~akpm/mmotm/broken-out/revert-mm-memcontrol-avoid-worklo… Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Johannes Weiner <hannes(a)cmpxchg.org> Subject: Revert "mm: memcontrol: avoid workload stalls when lowering memory.high" This reverts commit 536d3bf261a2fc3b05b3e91e7eef7383443015cf, as it can cause writers to memory.high to get stuck in the kernel forever, performing page reclaim and consuming excessive amounts of CPU cycles. Before the patch, a write to memory.high would first put the new limit in place for the workload, and then reclaim the requested delta. After the patch, the kernel tries to reclaim the delta before putting the new limit into place, in order to not overwhelm the workload with a sudden, large excess over the limit. However, if reclaim is actively racing with new allocations from the uncurbed workload, it can keep the write() working inside the kernel indefinitely. This is causing problems in Facebook production. A privileged system-level daemon that adjusts memory.high for various workloads running on a host can get unexpectedly stuck in the kernel and essentially turn into a sort of involuntary kswapd for one of the workloads. We've observed that daemon busy-spin in a write() for minutes at a time, neglecting its other duties on the system, and expending privileged system resources on behalf of a workload. To remedy this, we have first considered changing the reclaim logic to break out after a couple of loops - whether the workload has converged to the new limit or not - and bound the write() call this way. However, the root cause that inspired the sequence change in the first place has been fixed through other means, and so a revert back to the proven limit-setting sequence, also used by memory.max, is preferable. The sequence was changed to avoid extreme latencies in the workload when the limit was lowered: the sudden, large excess created by the limit lowering would erroneously trigger the penalty sleeping code that is meant to throttle excessive growth from below. Allocating threads could end up sleeping long after the write() had already reclaimed the delta for which they were being punished. However, erroneous throttling also caused problems in other scenarios at around the same time. This resulted in commit b3ff92916af3 ("mm, memcg: reclaim more aggressively before high allocator throttling"), included in the same release as the offending commit. When allocating threads now encounter large excess caused by a racing write() to memory.high, instead of entering punitive sleeps, they will simply be tasked with helping reclaim down the excess, and will be held no longer than it takes to accomplish that. This is in line with regular limit enforcement - i.e. if the workload allocates up against or over an otherwise unchanged limit from below. With the patch breaking userspace, and the root cause addressed by other means already, revert it again. Link: https://lkml.kernel.org/r/20210122184341.292461-1-hannes@cmpxchg.org Fixes: 536d3bf261a2 ("mm: memcontrol: avoid workload stalls when lowering memory.high") Signed-off-by: Johannes Weiner <hannes(a)cmpxchg.org> Reported-by: Tejun Heo <tj(a)kernel.org> Cc: Roman Gushchin <guro(a)fb.com> Cc: Michal Hocko <mhocko(a)suse.com> Cc: Shakeel Butt <shakeelb(a)google.com> Cc: Michal Koutný <mkoutny(a)suse.com> Cc: <stable(a)vger.kernel.org> [5.8+] Signed-off-by: Andrew Morton <akpm(a)linux-foundation.org> --- mm/memcontrol.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) --- a/mm/memcontrol.c~revert-mm-memcontrol-avoid-workload-stalls-when-lowering-memoryhigh +++ a/mm/memcontrol.c @@ -6271,6 +6271,8 @@ static ssize_t memory_high_write(struct if (err) return err; + page_counter_set_high(&memcg->memory, high); + for (;;) { unsigned long nr_pages = page_counter_read(&memcg->memory); @@ -6293,10 +6295,7 @@ static ssize_t memory_high_write(struct break; } - page_counter_set_high(&memcg->memory, high); - memcg_wb_domain_size_changed(memcg); - return nbytes; } _ Patches currently in -mm which might be from hannes(a)cmpxchg.org are mm-memcontrol-prevent-starvation-when-writing-memoryhigh.patch revert-mm-memcontrol-avoid-workload-stalls-when-lowering-memoryhigh.patch

4 years, 6 months

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