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Message-ID: <7c648dac-3198-3dba-0a96-34798cfdbd99@oppo.com>
Date: Tue, 20 Feb 2024 09:42:53 +0800
From: 李培锋 <lipeifeng@...o.com>
To: akpm@...ux-foundation.org, david@...hat.com, osalvador@...e.de,
willy@...radead.org
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org, tkjos@...gle.com,
surenb@...gle.com, gregkh@...gle.com, v-songbaohua@...o.com
Subject: Re: [PATCH 1/2] mm/rmap: support folio_referenced to control if
try_lock in rmap_walk
add more experts from Linux and Google.
在 2024/2/19 22:17, lipeifeng@...o.com 写道:
> From: lipeifeng <lipeifeng@...o.com>
>
> The patch to support folio_referenced to control the bevavior
> of walk_rmap, which for some thread to hold the lock in rmap_walk
> instead of try_lock when using folio_referenced.
>
> Signed-off-by: lipeifeng <lipeifeng@...o.com>
> ---
> include/linux/rmap.h | 5 +++--
> mm/rmap.c | 5 +++--
> mm/vmscan.c | 16 ++++++++++++++--
> 3 files changed, 20 insertions(+), 6 deletions(-)
>
> diff --git a/include/linux/rmap.h b/include/linux/rmap.h
> index b7944a8..846b261 100644
> --- a/include/linux/rmap.h
> +++ b/include/linux/rmap.h
> @@ -623,7 +623,8 @@ static inline int folio_try_share_anon_rmap_pmd(struct folio *folio,
> * Called from mm/vmscan.c to handle paging out
> */
> int folio_referenced(struct folio *, int is_locked,
> - struct mem_cgroup *memcg, unsigned long *vm_flags);
> + struct mem_cgroup *memcg, unsigned long *vm_flags,
> + unsigned int rw_try_lock);
>
> void try_to_migrate(struct folio *folio, enum ttu_flags flags);
> void try_to_unmap(struct folio *, enum ttu_flags flags);
> @@ -739,7 +740,7 @@ struct anon_vma *folio_lock_anon_vma_read(struct folio *folio,
>
> static inline int folio_referenced(struct folio *folio, int is_locked,
> struct mem_cgroup *memcg,
> - unsigned long *vm_flags)
> + unsigned long *vm_flags, unsigned int rw_try_lock)
> {
> *vm_flags = 0;
> return 0;
> diff --git a/mm/rmap.c b/mm/rmap.c
> index f5d43ed..15d1fba 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
> @@ -952,6 +952,7 @@ static bool invalid_folio_referenced_vma(struct vm_area_struct *vma, void *arg)
> * @is_locked: Caller holds lock on the folio.
> * @memcg: target memory cgroup
> * @vm_flags: A combination of all the vma->vm_flags which referenced the folio.
> + * @rw_try_lock: if try_lock in rmap_walk
> *
> * Quick test_and_clear_referenced for all mappings of a folio,
> *
> @@ -959,7 +960,7 @@ static bool invalid_folio_referenced_vma(struct vm_area_struct *vma, void *arg)
> * the function bailed out due to rmap lock contention.
> */
> int folio_referenced(struct folio *folio, int is_locked,
> - struct mem_cgroup *memcg, unsigned long *vm_flags)
> + struct mem_cgroup *memcg, unsigned long *vm_flags, unsigned int rw_try_lock)
> {
> int we_locked = 0;
> struct folio_referenced_arg pra = {
> @@ -970,7 +971,7 @@ int folio_referenced(struct folio *folio, int is_locked,
> .rmap_one = folio_referenced_one,
> .arg = (void *)&pra,
> .anon_lock = folio_lock_anon_vma_read,
> - .try_lock = true,
> + .try_lock = rw_try_lock ? true : false,
> .invalid_vma = invalid_folio_referenced_vma,
> };
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 4f9c854..0296d48 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -136,6 +136,9 @@ struct scan_control {
> /* Always discard instead of demoting to lower tier memory */
> unsigned int no_demotion:1;
>
> + /* if try_lock in rmap_walk */
> + unsigned int rw_try_lock:1;
> +
> /* Allocation order */
> s8 order;
>
> @@ -827,7 +830,7 @@ static enum folio_references folio_check_references(struct folio *folio,
> unsigned long vm_flags;
>
> referenced_ptes = folio_referenced(folio, 1, sc->target_mem_cgroup,
> - &vm_flags);
> + &vm_flags, sc->rw_try_lock);
> referenced_folio = folio_test_clear_referenced(folio);
>
> /*
> @@ -1501,6 +1504,7 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone,
> struct scan_control sc = {
> .gfp_mask = GFP_KERNEL,
> .may_unmap = 1,
> + .rw_try_lock = 1,
> };
> struct reclaim_stat stat;
> unsigned int nr_reclaimed;
> @@ -2038,7 +2042,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
>
> /* Referenced or rmap lock contention: rotate */
> if (folio_referenced(folio, 0, sc->target_mem_cgroup,
> - &vm_flags) != 0) {
> + &vm_flags, sc->rw_try_lock) != 0) {
> /*
> * Identify referenced, file-backed active folios and
> * give them one more trip around the active list. So
> @@ -2096,6 +2100,7 @@ static unsigned int reclaim_folio_list(struct list_head *folio_list,
> .may_unmap = 1,
> .may_swap = 1,
> .no_demotion = 1,
> + .rw_try_lock = 1,
> };
>
> nr_reclaimed = shrink_folio_list(folio_list, pgdat, &sc, &dummy_stat, false);
> @@ -5442,6 +5447,7 @@ static ssize_t lru_gen_seq_write(struct file *file, const char __user *src,
> .may_swap = true,
> .reclaim_idx = MAX_NR_ZONES - 1,
> .gfp_mask = GFP_KERNEL,
> + .rw_try_lock = 1,
> };
>
> buf = kvmalloc(len + 1, GFP_KERNEL);
> @@ -6414,6 +6420,7 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
> .may_writepage = !laptop_mode,
> .may_unmap = 1,
> .may_swap = 1,
> + .rw_try_lock = 1,
> };
>
> /*
> @@ -6459,6 +6466,7 @@ unsigned long mem_cgroup_shrink_node(struct mem_cgroup *memcg,
> .may_unmap = 1,
> .reclaim_idx = MAX_NR_ZONES - 1,
> .may_swap = !noswap,
> + .rw_try_lock = 1,
> };
>
> WARN_ON_ONCE(!current->reclaim_state);
> @@ -6503,6 +6511,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
> .may_unmap = 1,
> .may_swap = !!(reclaim_options & MEMCG_RECLAIM_MAY_SWAP),
> .proactive = !!(reclaim_options & MEMCG_RECLAIM_PROACTIVE),
> + .rw_try_lock = 1,
> };
> /*
> * Traverse the ZONELIST_FALLBACK zonelist of the current node to put
> @@ -6764,6 +6773,7 @@ static int balance_pgdat(pg_data_t *pgdat, int order, int highest_zoneidx)
> .gfp_mask = GFP_KERNEL,
> .order = order,
> .may_unmap = 1,
> + .rw_try_lock = 1,
> };
>
> set_task_reclaim_state(current, &sc.reclaim_state);
> @@ -7223,6 +7233,7 @@ unsigned long shrink_all_memory(unsigned long nr_to_reclaim)
> .may_unmap = 1,
> .may_swap = 1,
> .hibernation_mode = 1,
> + .rw_try_lock = 1,
> };
> struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask);
> unsigned long nr_reclaimed;
> @@ -7381,6 +7392,7 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in
> .may_unmap = !!(node_reclaim_mode & RECLAIM_UNMAP),
> .may_swap = 1,
> .reclaim_idx = gfp_zone(gfp_mask),
> + .rw_try_lock = 1,
> };
> unsigned long pflags;
>
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