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mm/page_alloc: avoid second trylock of zone->lock

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spin_trylock followed by spin_lock will cause extra write cache access. 
If the lock is contended it may cause unnecessary cache line bouncing and
will execute redundant irq restore/save pair.  Therefore, check
alloc/fpi_flags first and use spin_trylock or spin_lock.

Link: https://lkml.kernel.org/r/20250331002809.94758-1-alexei.starovoitov@gmail.com
Fixes: 97769a53f1 ("mm, bpf: Introduce try_alloc_pages() for opportunistic page allocation")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Daniel Borkman <daniel@iogearbox.net>
Cc: Martin KaFai Lau <martin.lau@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Alexei Starovoitov
2025-03-30 17:28:09 -07:00
committed by Andrew Morton
parent a84edd52f0
commit c5bb27e2da
1 changed files with 9 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files
mm/page_alloc.c
+9 -6
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@@ -1400,11 +1400,12 @@ static void free_one_page(struct zone *zone, struct page *page,
struct llist_head *llhead;
unsigned long flags;
if (!spin_trylock_irqsave(&zone->lock, flags)) {
if (unlikely(fpi_flags & FPI_TRYLOCK)) {
if (unlikely(fpi_flags & FPI_TRYLOCK)) {
if (!spin_trylock_irqsave(&zone->lock, flags)) {
add_page_to_zone_llist(zone, page, order);
return;
}
} else {
spin_lock_irqsave(&zone->lock, flags);
}
@@ -2314,9 +2315,10 @@ static int rmqueue_bulk(struct zone *zone, unsigned int order,
unsigned long flags;
int i;
if (!spin_trylock_irqsave(&zone->lock, flags)) {
if (unlikely(alloc_flags & ALLOC_TRYLOCK))
if (unlikely(alloc_flags & ALLOC_TRYLOCK)) {
if (!spin_trylock_irqsave(&zone->lock, flags))
return 0;
} else {
spin_lock_irqsave(&zone->lock, flags);
}
for (i = 0; i < count; ++i) {
@@ -2937,9 +2939,10 @@ struct page *rmqueue_buddy(struct zone *preferred_zone, struct zone *zone,
do {
page = NULL;
if (!spin_trylock_irqsave(&zone->lock, flags)) {
if (unlikely(alloc_flags & ALLOC_TRYLOCK))
if (unlikely(alloc_flags & ALLOC_TRYLOCK)) {
if (!spin_trylock_irqsave(&zone->lock, flags))
return NULL;
} else {
spin_lock_irqsave(&zone->lock, flags);
}
if (alloc_flags & ALLOC_HIGHATOMIC)