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-rw-r--r--fs/xfs/kmem.h2
-rw-r--r--include/linux/gfp.h8
-rw-r--r--include/linux/sched.h8
-rw-r--r--include/linux/sched/mm.h26
-rw-r--r--kernel/locking/lockdep.c6
-rw-r--r--mm/page_alloc.c10
-rw-r--r--mm/vmscan.c6
7 files changed, 47 insertions, 19 deletions
diff --git a/fs/xfs/kmem.h b/fs/xfs/kmem.h
index a6c8da40c70d..d6ea520162b2 100644
--- a/fs/xfs/kmem.h
+++ b/fs/xfs/kmem.h
@@ -50,7 +50,7 @@ kmem_flags_convert(xfs_km_flags_t flags)
lflags = GFP_ATOMIC | __GFP_NOWARN;
} else {
lflags = GFP_KERNEL | __GFP_NOWARN;
- if ((current->flags & PF_MEMALLOC_NOFS) || (flags & KM_NOFS))
+ if (flags & KM_NOFS)
lflags &= ~__GFP_FS;
}
diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 978232a3b4ae..2bfcfd33e476 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -210,8 +210,16 @@ struct vm_area_struct;
*
* GFP_NOIO will use direct reclaim to discard clean pages or slab pages
* that do not require the starting of any physical IO.
+ * Please try to avoid using this flag directly and instead use
+ * memalloc_noio_{save,restore} to mark the whole scope which cannot
+ * perform any IO with a short explanation why. All allocation requests
+ * will inherit GFP_NOIO implicitly.
*
* GFP_NOFS will use direct reclaim but will not use any filesystem interfaces.
+ * Please try to avoid using this flag directly and instead use
+ * memalloc_nofs_{save,restore} to mark the whole scope which cannot/shouldn't
+ * recurse into the FS layer with a short explanation why. All allocation
+ * requests will inherit GFP_NOFS implicitly.
*
* GFP_USER is for userspace allocations that also need to be directly
* accessibly by the kernel or hardware. It is typically used by hardware
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 8ac11465ac5b..993e7e25a3a5 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -1224,9 +1224,9 @@ extern struct pid *cad_pid;
#define PF_USED_ASYNC 0x00004000 /* Used async_schedule*(), used by module init */
#define PF_NOFREEZE 0x00008000 /* This thread should not be frozen */
#define PF_FROZEN 0x00010000 /* Frozen for system suspend */
-#define PF_FSTRANS 0x00020000 /* Inside a filesystem transaction */
-#define PF_KSWAPD 0x00040000 /* I am kswapd */
-#define PF_MEMALLOC_NOIO 0x00080000 /* Allocating memory without IO involved */
+#define PF_KSWAPD 0x00020000 /* I am kswapd */
+#define PF_MEMALLOC_NOFS 0x00040000 /* All allocation requests will inherit GFP_NOFS */
+#define PF_MEMALLOC_NOIO 0x00080000 /* All allocation requests will inherit GFP_NOIO */
#define PF_LESS_THROTTLE 0x00100000 /* Throttle me less: I clean memory */
#define PF_KTHREAD 0x00200000 /* I am a kernel thread */
#define PF_RANDOMIZE 0x00400000 /* Randomize virtual address space */
@@ -1237,8 +1237,6 @@ extern struct pid *cad_pid;
#define PF_FREEZER_SKIP 0x40000000 /* Freezer should not count it as freezable */
#define PF_SUSPEND_TASK 0x80000000 /* This thread called freeze_processes() and should not be frozen */
-#define PF_MEMALLOC_NOFS PF_FSTRANS /* Transition to a more generic GFP_NOFS scope semantic */
-
/*
* Only the _current_ task can read/write to tsk->flags, but other
* tasks can access tsk->flags in readonly mode for example
diff --git a/include/linux/sched/mm.h b/include/linux/sched/mm.h
index 830953ebb391..9daabe138c99 100644
--- a/include/linux/sched/mm.h
+++ b/include/linux/sched/mm.h
@@ -149,13 +149,21 @@ static inline bool in_vfork(struct task_struct *tsk)
return ret;
}
-/* __GFP_IO isn't allowed if PF_MEMALLOC_NOIO is set in current->flags
- * __GFP_FS is also cleared as it implies __GFP_IO.
+/*
+ * Applies per-task gfp context to the given allocation flags.
+ * PF_MEMALLOC_NOIO implies GFP_NOIO
+ * PF_MEMALLOC_NOFS implies GFP_NOFS
*/
-static inline gfp_t memalloc_noio_flags(gfp_t flags)
+static inline gfp_t current_gfp_context(gfp_t flags)
{
+ /*
+ * NOIO implies both NOIO and NOFS and it is a weaker context
+ * so always make sure it makes precendence
+ */
if (unlikely(current->flags & PF_MEMALLOC_NOIO))
flags &= ~(__GFP_IO | __GFP_FS);
+ else if (unlikely(current->flags & PF_MEMALLOC_NOFS))
+ flags &= ~__GFP_FS;
return flags;
}
@@ -171,4 +179,16 @@ static inline void memalloc_noio_restore(unsigned int flags)
current->flags = (current->flags & ~PF_MEMALLOC_NOIO) | flags;
}
+static inline unsigned int memalloc_nofs_save(void)
+{
+ unsigned int flags = current->flags & PF_MEMALLOC_NOFS;
+ current->flags |= PF_MEMALLOC_NOFS;
+ return flags;
+}
+
+static inline void memalloc_nofs_restore(unsigned int flags)
+{
+ current->flags = (current->flags & ~PF_MEMALLOC_NOFS) | flags;
+}
+
#endif /* _LINUX_SCHED_MM_H */
diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c
index f84294c9a018..fd440b5a3c75 100644
--- a/kernel/locking/lockdep.c
+++ b/kernel/locking/lockdep.c
@@ -2877,7 +2877,7 @@ static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
if (unlikely(!debug_locks))
return;
- gfp_mask = memalloc_noio_flags(gfp_mask);
+ gfp_mask = current_gfp_context(gfp_mask);
/* no reclaim without waiting on it */
if (!(gfp_mask & __GFP_DIRECT_RECLAIM))
@@ -2888,7 +2888,7 @@ static void __lockdep_trace_alloc(gfp_t gfp_mask, unsigned long flags)
return;
/* We're only interested __GFP_FS allocations for now */
- if (!(gfp_mask & __GFP_FS))
+ if (!(gfp_mask & __GFP_FS) || (curr->flags & PF_MEMALLOC_NOFS))
return;
/*
@@ -3954,7 +3954,7 @@ EXPORT_SYMBOL_GPL(lock_unpin_lock);
void lockdep_set_current_reclaim_state(gfp_t gfp_mask)
{
- current->lockdep_reclaim_gfp = memalloc_noio_flags(gfp_mask);
+ current->lockdep_reclaim_gfp = current_gfp_context(gfp_mask);
}
void lockdep_clear_current_reclaim_state(void)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 34ac32428de8..7a3751e53f91 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -3951,10 +3951,12 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
goto out;
/*
- * Runtime PM, block IO and its error handling path can deadlock
- * because I/O on the device might not complete.
+ * Apply scoped allocation constraints. This is mainly about GFP_NOFS
+ * resp. GFP_NOIO which has to be inherited for all allocation requests
+ * from a particular context which has been marked by
+ * memalloc_no{fs,io}_{save,restore}.
*/
- alloc_mask = memalloc_noio_flags(gfp_mask);
+ alloc_mask = current_gfp_context(gfp_mask);
ac.spread_dirty_pages = false;
/*
@@ -7408,7 +7410,7 @@ int alloc_contig_range(unsigned long start, unsigned long end,
.zone = page_zone(pfn_to_page(start)),
.mode = MIGRATE_SYNC,
.ignore_skip_hint = true,
- .gfp_mask = memalloc_noio_flags(gfp_mask),
+ .gfp_mask = current_gfp_context(gfp_mask),
};
INIT_LIST_HEAD(&cc.migratepages);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index ec4555369e17..3ad66580b8b4 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2915,7 +2915,7 @@ unsigned long try_to_free_pages(struct zonelist *zonelist, int order,
unsigned long nr_reclaimed;
struct scan_control sc = {
.nr_to_reclaim = SWAP_CLUSTER_MAX,
- .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)),
+ .gfp_mask = (gfp_mask = current_gfp_context(gfp_mask)),
.reclaim_idx = gfp_zone(gfp_mask),
.order = order,
.nodemask = nodemask,
@@ -2995,7 +2995,7 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg,
int nid;
struct scan_control sc = {
.nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
- .gfp_mask = (gfp_mask & GFP_RECLAIM_MASK) |
+ .gfp_mask = (current_gfp_context(gfp_mask) & GFP_RECLAIM_MASK) |
(GFP_HIGHUSER_MOVABLE & ~GFP_RECLAIM_MASK),
.reclaim_idx = MAX_NR_ZONES - 1,
.target_mem_cgroup = memcg,
@@ -3702,7 +3702,7 @@ static int __node_reclaim(struct pglist_data *pgdat, gfp_t gfp_mask, unsigned in
int classzone_idx = gfp_zone(gfp_mask);
struct scan_control sc = {
.nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX),
- .gfp_mask = (gfp_mask = memalloc_noio_flags(gfp_mask)),
+ .gfp_mask = (gfp_mask = current_gfp_context(gfp_mask)),
.order = order,
.priority = NODE_RECLAIM_PRIORITY,
.may_writepage = !!(node_reclaim_mode & RECLAIM_WRITE),
generated by cgit v1.2.3-55-g7522 (git 2.39.0) at 2024-06-08 08:29:26 +0200