From: Stefan Roesch <shr@devkernel.io> mainline inclusion from mainline-v6.7-rc1 commit 3c6f33b7273a7e2f2b2497b62c8400bd957b2fbe category: feature bugzilla: https://atomgit.com/openeuler/kernel/issues/10169 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- Patch series "mm/ksm: add fork-exec support for prctl", v4. A process can enable KSM with the prctl system call. When the process is forked the KSM flag is inherited by the child process. However if the process is executing an exec system call directly after the fork, the KSM setting is cleared. This patch series addresses this problem. 1) Change the mask in coredump.h for execing a new process 2) Add a new test case in ksm_functional_tests This patch (of 2): Today we have two ways to enable KSM: 1) madvise system call This allows to enable KSM for a memory region for a long time. 2) prctl system call This is a recent addition to enable KSM for the complete process. In addition when a process is forked, the KSM setting is inherited. This change only affects the second case. One of the use cases for (2) was to support the ability to enable KSM for cgroups. This allows systemd to enable KSM for the seed process. By enabling it in the seed process all child processes inherit the setting. This works correctly when the process is forked. However it doesn't support fork/exec workflow. From the previous cover letter: .... Use case 3: With the madvise call sharing opportunities are only enabled for the current process: it is a workload-local decision. A considerable number of sharing opportunities may exist across multiple workloads or jobs (if they are part of the same security domain). Only a higler level entity like a job scheduler or container can know for certain if its running one or more instances of a job. That job scheduler however doesn't have the necessary internal workload knowledge to make targeted madvise calls. .... In addition it can also be a bit surprising that fork keeps the KSM setting and fork/exec does not. Link: https://lkml.kernel.org/r/20230922211141.320789-1-shr@devkernel.io Link: https://lkml.kernel.org/r/20230922211141.320789-2-shr@devkernel.io Signed-off-by: Stefan Roesch <shr@devkernel.io> Fixes: d7597f59d1d3 ("mm: add new api to enable ksm per process") Reviewed-by: David Hildenbrand <david@redhat.com> Reported-by: Carl Klemm <carl@uvos.xyz> Tested-by: Carl Klemm <carl@uvos.xyz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Rik van Riel <riel@surriel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Conflicts: include/linux/sched/coredump.h [Context conflicts.] Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com> --- include/linux/sched/coredump.h | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/include/linux/sched/coredump.h b/include/linux/sched/coredump.h index 28d71cc496bc..097f323fee54 100644 --- a/include/linux/sched/coredump.h +++ b/include/linux/sched/coredump.h @@ -71,6 +71,7 @@ static inline int get_dumpable(struct mm_struct *mm) #define MMF_UNSTABLE 22 /* mm is unstable for copy_from_user */ #define MMF_HUGE_ZERO_PAGE 23 /* mm has ever used the global huge zero page */ #define MMF_DISABLE_THP 24 /* disable THP for all VMAs */ +#define MMF_DISABLE_THP_MASK (1 << MMF_DISABLE_THP) #define MMF_OOM_REAP_QUEUED 25 /* mm was queued for oom_reaper */ #define MMF_MULTIPROCESS 26 /* mm is shared between processes */ /* @@ -85,12 +86,13 @@ static inline int get_dumpable(struct mm_struct *mm) #define MMF_HAS_MDWE 28 #define MMF_HAS_MDWE_MASK (1 << MMF_HAS_MDWE) -#define MMF_DISABLE_THP_MASK (1 << MMF_DISABLE_THP) +#define MMF_VM_MERGE_ANY 29 +#define MMF_VM_MERGE_ANY_MASK (1 << MMF_VM_MERGE_ANY) #define MMF_INIT_MASK (MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK |\ - MMF_DISABLE_THP_MASK | MMF_HAS_MDWE_MASK) + MMF_DISABLE_THP_MASK | MMF_HAS_MDWE_MASK |\ + MMF_VM_MERGE_ANY_MASK) -#define MMF_VM_MERGE_ANY 29 #define MMF_HAS_MDWE_NO_INHERIT 30 #ifdef CONFIG_ACPI_APEI_RAS_CRITICAL -- 2.43.0

From: Chengming Zhou <chengming.zhou@linux.dev> mainline inclusion from mainline-v6.11-rc1 commit ac90c56bbd734addc9bfb4567f64f1c180c64f5d category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/10169 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- Patch series "mm/ksm: cmp_and_merge_page() optimizations and cleanup", v2. This series mainly optimizes cmp_and_merge_page() to have more efficient separate code flow for ksm page and non-ksm anon page. - ksm page: don't need to calculate the checksum obviously. - anon page: don't need to search stable tree if changing fast and try to merge with zero page before searching ksm page on stable tree. Please see the patch-2 for details. Patch-3 is cleanup also a little optimization for the chain()/chain_prune interfaces, which made the stable_tree_search()/stable_tree_insert() over complex. I have done simple testing using "hackbench -g 1 -l 300000" (maybe I need to use a better workload) on my machine, have seen a little CPU usage decrease of ksmd and some improvements of cmp_and_merge_page() latency: We can see the latency of cmp_and_merge_page() when handling non-ksm anon pages has been improved. This patch (of 3): In preparation for later changes, refactor out a new function called try_to_merge_with_zero_page(), which tries to merge with zero page. Link: https://lkml.kernel.org/r/20240621-b4-ksm-scan-optimize-v2-0-1c328aa9e30b@li... Link: https://lkml.kernel.org/r/20240621-b4-ksm-scan-optimize-v2-1-1c328aa9e30b@li... Signed-off-by: Chengming Zhou <chengming.zhou@linux.dev> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Stefan Roesch <shr@devkernel.io> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com> --- mm/hugetlb.c | 1 - mm/ksm.c | 70 ++++++++++++++++++++++++++++++---------------------- 2 files changed, 40 insertions(+), 31 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index f9ecf50a8f74..88164254cebc 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -2703,7 +2703,6 @@ static int gather_surplus_pages(struct hstate *h, long delta) retry: spin_unlock_irq(&hugetlb_lock); for (i = 0; i < needed; i++) { - folio = NULL; for_each_node_mask(node, cpuset_current_mems_allowed) { if (!mbind_nodemask || node_isset(node, *mbind_nodemask)) { folio = alloc_surplus_hugetlb_folio(h, htlb_alloc_mask(h), diff --git a/mm/ksm.c b/mm/ksm.c index 0de3de6df144..7e1738b0fb69 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -1347,6 +1347,44 @@ static int try_to_merge_one_page(struct vm_area_struct *vma, return err; } +/* + * This function returns 0 if the pages were merged or if they are + * no longer merging candidates (e.g., VMA stale), -EFAULT otherwise. + */ +static int try_to_merge_with_zero_page(struct ksm_rmap_item *rmap_item, + struct page *page) +{ + struct mm_struct *mm = rmap_item->mm; + int err = -EFAULT; + + /* + * Same checksum as an empty page. We attempt to merge it with the + * appropriate zero page if the user enabled this via sysfs. + */ + if (ksm_use_zero_pages && (rmap_item->oldchecksum == zero_checksum)) { + struct vm_area_struct *vma; + + mmap_read_lock(mm); + vma = find_mergeable_vma(mm, rmap_item->address); + if (vma) { + err = try_to_merge_one_page(vma, page, + ZERO_PAGE(rmap_item->address)); + trace_ksm_merge_one_page( + page_to_pfn(ZERO_PAGE(rmap_item->address)), + rmap_item, mm, err); + } else { + /* + * If the vma is out of date, we do not need to + * continue. + */ + err = 0; + } + mmap_read_unlock(mm); + } + + return err; +} + /* * try_to_merge_with_ksm_page - like try_to_merge_two_pages, * but no new kernel page is allocated: kpage must already be a ksm page. @@ -2117,7 +2155,6 @@ static void stable_tree_append(struct ksm_rmap_item *rmap_item, */ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_item) { - struct mm_struct *mm = rmap_item->mm; struct ksm_rmap_item *tree_rmap_item; struct page *tree_page = NULL; struct ksm_stable_node *stable_node; @@ -2186,36 +2223,9 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite return; } - /* - * Same checksum as an empty page. We attempt to merge it with the - * appropriate zero page if the user enabled this via sysfs. - */ - if (ksm_use_zero_pages && (checksum == zero_checksum)) { - struct vm_area_struct *vma; + if (!try_to_merge_with_zero_page(rmap_item, page)) + return; - mmap_read_lock(mm); - vma = find_mergeable_vma(mm, rmap_item->address); - if (vma) { - err = try_to_merge_one_page(vma, page, - ZERO_PAGE(rmap_item->address)); - trace_ksm_merge_one_page( - page_to_pfn(ZERO_PAGE(rmap_item->address)), - rmap_item, mm, err); - } else { - /* - * If the vma is out of date, we do not need to - * continue. - */ - err = 0; - } - mmap_read_unlock(mm); - /* - * In case of failure, the page was not really empty, so we - * need to continue. Otherwise we're done. - */ - if (!err) - return; - } tree_rmap_item = unstable_tree_search_insert(rmap_item, page, &tree_page); if (tree_rmap_item) { -- 2.43.0

From: Chengming Zhou <chengming.zhou@linux.dev> mainline inclusion from mainline-v6.11-rc1 commit d58a361b0350128bf5a5cf47773edaedbb6ea838 category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/10169 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- The code flow in cmp_and_merge_page() is suboptimal for handling the ksm page and non-ksm page at the same time. For example: - ksm page 1. Mostly just return if this ksm page is not migrated and this rmap_item has been on the rmap hlist. Or we have to fix this rmap_item mapping. 2. But we absolutely don't need to checksum for this ksm page, since it can't change. - non-ksm page 1. First don't need to waste time searching stable tree if fast changing. 2. Should try to merge with zero page before search the stable tree. 3. Then search stable tree to find mergeable ksm page. This patch optimizes the code flow so the handling differences between ksm page and non-ksm page become clearer and more efficient too. Link: https://lkml.kernel.org/r/20240621-b4-ksm-scan-optimize-v2-2-1c328aa9e30b@li... Signed-off-by: Chengming Zhou <chengming.zhou@linux.dev> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Stefan Roesch <shr@devkernel.io> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com> --- mm/ksm.c | 32 +++++++++++++++++--------------- 1 file changed, 17 insertions(+), 15 deletions(-) diff --git a/mm/ksm.c b/mm/ksm.c index 7e1738b0fb69..e73cdde7b537 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -2181,6 +2181,23 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite */ if (!is_page_sharing_candidate(stable_node)) max_page_sharing_bypass = true; + } else { + remove_rmap_item_from_tree(rmap_item); + + /* + * If the hash value of the page has changed from the last time + * we calculated it, this page is changing frequently: therefore we + * don't want to insert it in the unstable tree, and we don't want + * to waste our time searching for something identical to it there. + */ + checksum = calc_checksum(page); + if (rmap_item->oldchecksum != checksum) { + rmap_item->oldchecksum = checksum; + return; + } + + if (!try_to_merge_with_zero_page(rmap_item, page)) + return; } /* We first start with searching the page inside the stable tree */ @@ -2211,21 +2228,6 @@ static void cmp_and_merge_page(struct page *page, struct ksm_rmap_item *rmap_ite return; } - /* - * If the hash value of the page has changed from the last time - * we calculated it, this page is changing frequently: therefore we - * don't want to insert it in the unstable tree, and we don't want - * to waste our time searching for something identical to it there. - */ - checksum = calc_checksum(page); - if (rmap_item->oldchecksum != checksum) { - rmap_item->oldchecksum = checksum; - return; - } - - if (!try_to_merge_with_zero_page(rmap_item, page)) - return; - tree_rmap_item = unstable_tree_search_insert(rmap_item, page, &tree_page); if (tree_rmap_item) { -- 2.43.0

hulk inclusion category: feature bugzilla: https://atomgit.com/openeuler/kernel/issues/10169 ---------------------------------------- When a task moves to a new memcg, enable KSM for the task if the auto_ksm_enabled of the memcg is 1. Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com> --- mm/memcontrol.c | 37 ++++++++++++++++++++++++++++++++++++- 1 file changed, 36 insertions(+), 1 deletion(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 7ca63824ab74..675243166542 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -6064,6 +6064,39 @@ static ssize_t memory_ksm_write(struct kernfs_open_file *of, char *buf, return nbytes; } + +static void memcg_attach_ksm(struct cgroup_taskset *tset) +{ + struct cgroup_subsys_state *css; + struct mem_cgroup *memcg; + struct task_struct *task; + + cgroup_taskset_first(tset, &css); + memcg = mem_cgroup_from_css(css); + if (!READ_ONCE(memcg->auto_ksm_enabled)) + return; + + cgroup_taskset_for_each(task, css, tset) { + struct mm_struct *mm = get_task_mm(task); + + if (!mm) + continue; + + if (mmap_write_lock_killable(mm)) { + mmput(mm); + continue; + } + + ksm_enable_merge_any(mm); + + mmap_write_unlock(mm); + mmput(mm); + } +} +#else +static inline void memcg_attach_ksm(struct cgroup_taskset *tset) +{ +} #endif /* CONFIG_KSM */ #ifdef CONFIG_DYNAMIC_POOL @@ -7910,6 +7943,8 @@ static void mem_cgroup_attach(struct cgroup_taskset *tset) { mem_cgroup_lru_gen_attach(tset); mem_cgroup_kmem_attach(tset); + if (!cgroup_subsys_on_dfl(memory_cgrp_subsys)) + memcg_attach_ksm(tset); } #endif @@ -8401,7 +8436,7 @@ struct cgroup_subsys memory_cgrp_subsys = { .css_reset = mem_cgroup_css_reset, .css_rstat_flush = mem_cgroup_css_rstat_flush, .can_attach = mem_cgroup_can_attach, -#if defined(CONFIG_LRU_GEN) || defined(CONFIG_MEMCG_KMEM) +#if defined(CONFIG_LRU_GEN) || defined(CONFIG_MEMCG_KMEM) || defined(CONFIG_KSM) .attach = mem_cgroup_attach, #endif .cancel_attach = mem_cgroup_cancel_attach, -- 2.43.0

From: Johannes Weiner <hannes@cmpxchg.org> mainline inclusion from mainline-v6.18-rc1 commit 19c5fb83f2a4dde7b53b3aeb1fa87bfa3559286b category: bugfix bugzilla: https://atomgit.com/openeuler/kernel/issues/10169 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- On NUMA systems without bindings, allocations check all nodes for free space, then wake up the kswapds on all nodes and retry. This ensures all available space is evenly used before reclaim begins. However, when one process or certain allocations have node restrictions, they can cause kswapds on only a subset of nodes to be woken up. Since kswapd hysteresis targets watermarks that are *higher* than needed for allocation, even *unrestricted* allocations can now get suckered onto such nodes that are already pressured. This ends up concentrating all allocations on them, even when there are idle nodes available for the unrestricted requests. This was observed with two numa nodes, where node0 is normal and node1 is ZONE_MOVABLE to facilitate hotplugging: a kernel allocation wakes kswapd on node0 only (since node1 is not eligible); once kswapd0 is active, the watermarks hover between low and high, and then even the movable allocations end up on node0, only to be kicked out again; meanwhile node1 is empty and idle. Similar behavior is possible when a process with NUMA bindings is causing selective kswapd wakeups. To fix this, on NUMA systems augment the (misleading) watermark test with a check for whether kswapd is already active during the first iteration through the zonelist. If this fails to place the request, kswapd must be running everywhere already, and the watermark test is good enough to decide placement. With this patch, unrestricted requests successfully make use of node1, even while kswapd is reclaiming node0 for restricted allocations. [gourry@gourry.net: don't retry if no kswapds were active] Link: https://lkml.kernel.org/r/20250919162134.1098208-1-hannes@cmpxchg.org Signed-off-by: Gregory Price <gourry@gourry.net> Tested-by: Joshua Hahn <joshua.hahnjy@gmail.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Zi Yan <ziy@nvidia.com> Cc: Brendan Jackman <jackmanb@google.com> Cc: Joshua Hahn <joshua.hahnjy@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Conflicts: mm/page_alloc.c [Context conflicts.] Signed-off-by: Jinjiang Tu <tujinjiang@huawei.com> --- mm/page_alloc.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 596f0f1e4017..b1ffe4ea5e66 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3414,6 +3414,8 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags, struct pglist_data *last_pgdat = NULL; bool last_pgdat_dirty_ok = false; bool no_fallback; + bool skip_kswapd_nodes = nr_online_nodes > 1; + bool skipped_kswapd_nodes = false; retry: /* @@ -3480,6 +3482,19 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags, } } + /* + * If kswapd is already active on a node, keep looking + * for other nodes that might be idle. This can happen + * if another process has NUMA bindings and is causing + * kswapd wakeups on only some nodes. Avoid accidental + * "node_reclaim_mode"-like behavior in this case. + */ + if (skip_kswapd_nodes && + !waitqueue_active(&zone->zone_pgdat->kswapd_wait)) { + skipped_kswapd_nodes = true; + continue; + } + cond_accept_memory(zone, order); /* @@ -3582,6 +3597,15 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags, } } + /* + * If we skipped over nodes with active kswapds and found no + * idle nodes, retry and place anywhere the watermarks permit. + */ + if (skip_kswapd_nodes && skipped_kswapd_nodes) { + skip_kswapd_nodes = false; + goto retry; + } + /* * It's possible on a UMA machine to get through all zones that are * fragmented. If avoiding fragmentation, reset and try again. -- 2.43.0