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charset=us-ascii Content-Disposition: inline In-Reply-To: <20241230174621.61185-9-ryncsn@gmail.com> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 X-Rspamd-Server: rspam05 X-Stat-Signature: uf68qj3kcpbse8cmw3z31mg5nherpux1 X-Rspamd-Queue-Id: EEC6240006 X-Rspam-User: X-HE-Tag: 1736152998-618004 X-HE-Meta: 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 rN4O0Sz4 MIuHy2+rczz79eLMqU9cjI19YWNuwaxw0UWed64ucR0lRDR0ix7HRHRW9TlzPwzqosbqEUR+4ZgYzDlKMKpOQt//0+/UI0qf1BNykO6ymNDXS3jbQS+09OPayeGxy1wiS3PJkKaQ2GLqnjrkNrwg8DJpwx3SKc6NXG7vqyzxyee4c6Y0XItpbWyPlhKQo8Cb11WUdFK0jUNcYDV+NoWaVluUuhh4d6Noq9RyYRU0VzkE50IUgUZXgBhFN/XsLWPUz0Hm0A5JAB+5q7gBpKD9gnaGM29l9uJo1/DNIXJfKebECvJEvommKQcZzaIpD63DVszY2uJuMwdZvLChcETSsDqA3KUKEA5hGZxKzVZ0ZwGGWFxKBxaVmqcS8YQBtCRADiMgpNUmAOdbHOBs= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 12/31/24 at 01:46am, Kairui Song wrote: > From: Kairui Song > > Currently, we are only using flags to indicate which list the cluster > is on. Using one bit for each list type might be a waste, as the list > type grows, we will consume too many bits. Additionally, the current > mixed usage of '&' and '==' is a bit confusing. I think this kind of converting can only happen when the type is exclusive on each cluster. Then we can set and use 'ci->flags == CLUSTER_FLAG_XXX' to check it. > > Make it clean by using an enum to define all possible cluster > statuses. Only an off-list cluster will have the NONE (0) flag. > And use a wrapper to annotate and sanitize all flag settings > and list movements. > > Suggested-by: Chris Li > Signed-off-by: Kairui Song > --- > include/linux/swap.h | 17 +++++++--- > mm/swapfile.c | 75 +++++++++++++++++++++++--------------------- > 2 files changed, 52 insertions(+), 40 deletions(-) > > diff --git a/include/linux/swap.h b/include/linux/swap.h > index 02120f1005d5..339d7f0192ff 100644 > --- a/include/linux/swap.h > +++ b/include/linux/swap.h > @@ -257,10 +257,19 @@ struct swap_cluster_info { > u8 order; > struct list_head list; > }; > -#define CLUSTER_FLAG_FREE 1 /* This cluster is free */ > -#define CLUSTER_FLAG_NONFULL 2 /* This cluster is on nonfull list */ > -#define CLUSTER_FLAG_FRAG 4 /* This cluster is on nonfull list */ > -#define CLUSTER_FLAG_FULL 8 /* This cluster is on full list */ > + > +/* All on-list cluster must have a non-zero flag. */ > +enum swap_cluster_flags { > + CLUSTER_FLAG_NONE = 0, /* For temporary off-list cluster */ > + CLUSTER_FLAG_FREE, > + CLUSTER_FLAG_NONFULL, > + CLUSTER_FLAG_FRAG, > + /* Clusters with flags above are allocatable */ > + CLUSTER_FLAG_USABLE = CLUSTER_FLAG_FRAG, > + CLUSTER_FLAG_FULL, > + CLUSTER_FLAG_DISCARD, > + CLUSTER_FLAG_MAX, > +}; > > /* > * The first page in the swap file is the swap header, which is always marked > diff --git a/mm/swapfile.c b/mm/swapfile.c > index 99fd0b0d84a2..7795a3d27273 100644 > --- a/mm/swapfile.c > +++ b/mm/swapfile.c > @@ -403,7 +403,7 @@ static void discard_swap_cluster(struct swap_info_struct *si, > > static inline bool cluster_is_free(struct swap_cluster_info *info) > { > - return info->flags & CLUSTER_FLAG_FREE; > + return info->flags == CLUSTER_FLAG_FREE; > } > > static inline unsigned int cluster_index(struct swap_info_struct *si, > @@ -434,6 +434,27 @@ static inline void unlock_cluster(struct swap_cluster_info *ci) > spin_unlock(&ci->lock); > } > > +static void cluster_move(struct swap_info_struct *si, ~~~~~~~~~~~~ Maybe rename it to move_cluster() which has the same naming style as lock_cluster()/unlock_cluster()? This is what we usually do namin if a function is action acts on objects. Other than this, this patch looks great to me. > + struct swap_cluster_info *ci, struct list_head *list, > + enum swap_cluster_flags new_flags) > +{ > + VM_WARN_ON(ci->flags == new_flags); > + BUILD_BUG_ON(1 << sizeof(ci->flags) * BITS_PER_BYTE < CLUSTER_FLAG_MAX); > + > + if (ci->flags == CLUSTER_FLAG_NONE) { > + list_add_tail(&ci->list, list); > + } else { > + if (ci->flags == CLUSTER_FLAG_FRAG) { > + VM_WARN_ON(!si->frag_cluster_nr[ci->order]); > + si->frag_cluster_nr[ci->order]--; > + } > + list_move_tail(&ci->list, list); > + } > + ci->flags = new_flags; > + if (new_flags == CLUSTER_FLAG_FRAG) > + si->frag_cluster_nr[ci->order]++; > +} > + > /* Add a cluster to discard list and schedule it to do discard */ > static void swap_cluster_schedule_discard(struct swap_info_struct *si, > struct swap_cluster_info *ci) > @@ -447,10 +468,8 @@ static void swap_cluster_schedule_discard(struct swap_info_struct *si, > */ > memset(si->swap_map + idx * SWAPFILE_CLUSTER, > SWAP_MAP_BAD, SWAPFILE_CLUSTER); > - > - VM_BUG_ON(ci->flags & CLUSTER_FLAG_FREE); > - list_move_tail(&ci->list, &si->discard_clusters); > - ci->flags = 0; > + VM_BUG_ON(ci->flags == CLUSTER_FLAG_FREE); > + cluster_move(si, ci, &si->discard_clusters, CLUSTER_FLAG_DISCARD); > schedule_work(&si->discard_work); > } > > @@ -458,12 +477,7 @@ static void __free_cluster(struct swap_info_struct *si, struct swap_cluster_info > { > lockdep_assert_held(&si->lock); > lockdep_assert_held(&ci->lock); > - > - if (ci->flags) > - list_move_tail(&ci->list, &si->free_clusters); > - else > - list_add_tail(&ci->list, &si->free_clusters); > - ci->flags = CLUSTER_FLAG_FREE; > + cluster_move(si, ci, &si->free_clusters, CLUSTER_FLAG_FREE); > ci->order = 0; > } > > @@ -479,6 +493,8 @@ static void swap_do_scheduled_discard(struct swap_info_struct *si) > while (!list_empty(&si->discard_clusters)) { > ci = list_first_entry(&si->discard_clusters, struct swap_cluster_info, list); > list_del(&ci->list); > + /* Must clear flag when taking a cluster off-list */ > + ci->flags = CLUSTER_FLAG_NONE; > idx = cluster_index(si, ci); > spin_unlock(&si->lock); > > @@ -519,9 +535,6 @@ static void free_cluster(struct swap_info_struct *si, struct swap_cluster_info * > lockdep_assert_held(&si->lock); > lockdep_assert_held(&ci->lock); > > - if (ci->flags & CLUSTER_FLAG_FRAG) > - si->frag_cluster_nr[ci->order]--; > - > /* > * If the swap is discardable, prepare discard the cluster > * instead of free it immediately. The cluster will be freed > @@ -573,13 +586,9 @@ static void dec_cluster_info_page(struct swap_info_struct *si, > return; > } > > - if (!(ci->flags & CLUSTER_FLAG_NONFULL)) { > - VM_BUG_ON(ci->flags & CLUSTER_FLAG_FREE); > - if (ci->flags & CLUSTER_FLAG_FRAG) > - si->frag_cluster_nr[ci->order]--; > - list_move_tail(&ci->list, &si->nonfull_clusters[ci->order]); > - ci->flags = CLUSTER_FLAG_NONFULL; > - } > + if (ci->flags != CLUSTER_FLAG_NONFULL) > + cluster_move(si, ci, &si->nonfull_clusters[ci->order], > + CLUSTER_FLAG_NONFULL); > } > > static bool cluster_reclaim_range(struct swap_info_struct *si, > @@ -663,11 +672,13 @@ static bool cluster_alloc_range(struct swap_info_struct *si, struct swap_cluster > if (!(si->flags & SWP_WRITEOK)) > return false; > > + VM_BUG_ON(ci->flags == CLUSTER_FLAG_NONE); > + VM_BUG_ON(ci->flags > CLUSTER_FLAG_USABLE); > + > if (cluster_is_free(ci)) { > - if (nr_pages < SWAPFILE_CLUSTER) { > - list_move_tail(&ci->list, &si->nonfull_clusters[order]); > - ci->flags = CLUSTER_FLAG_NONFULL; > - } > + if (nr_pages < SWAPFILE_CLUSTER) > + cluster_move(si, ci, &si->nonfull_clusters[order], > + CLUSTER_FLAG_NONFULL); > ci->order = order; > } > > @@ -675,14 +686,8 @@ static bool cluster_alloc_range(struct swap_info_struct *si, struct swap_cluster > swap_range_alloc(si, nr_pages); > ci->count += nr_pages; > > - if (ci->count == SWAPFILE_CLUSTER) { > - VM_BUG_ON(!(ci->flags & > - (CLUSTER_FLAG_FREE | CLUSTER_FLAG_NONFULL | CLUSTER_FLAG_FRAG))); > - if (ci->flags & CLUSTER_FLAG_FRAG) > - si->frag_cluster_nr[ci->order]--; > - list_move_tail(&ci->list, &si->full_clusters); > - ci->flags = CLUSTER_FLAG_FULL; > - } > + if (ci->count == SWAPFILE_CLUSTER) > + cluster_move(si, ci, &si->full_clusters, CLUSTER_FLAG_FULL); > > return true; > } > @@ -821,9 +826,7 @@ static unsigned long cluster_alloc_swap_entry(struct swap_info_struct *si, int o > while (!list_empty(&si->nonfull_clusters[order])) { > ci = list_first_entry(&si->nonfull_clusters[order], > struct swap_cluster_info, list); > - list_move_tail(&ci->list, &si->frag_clusters[order]); > - ci->flags = CLUSTER_FLAG_FRAG; > - si->frag_cluster_nr[order]++; > + cluster_move(si, ci, &si->frag_clusters[order], CLUSTER_FLAG_FRAG); > offset = alloc_swap_scan_cluster(si, cluster_offset(si, ci), > &found, order, usage); > frags++; > -- > 2.47.1 > >