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Message-ID:
<VI2PR04MB11147FA8008C118F375650623E8AE2@VI2PR04MB11147.eurprd04.prod.outlook.com>
Date: Thu, 3 Apr 2025 09:23:55 +0000
From: Carlos Song <carlos.song@....com>
To: Johannes Weiner <hannes@...xchg.org>
CC: "baolin.wang@...ux.alibaba.com" <baolin.wang@...ux.alibaba.com>,
"ying.huang@...el.com" <ying.huang@...el.com>, "vbabka@...e.cz"
<vbabka@...e.cz>, "david@...hat.com" <david@...hat.com>,
"mgorman@...hsingularity.net" <mgorman@...hsingularity.net>, "ziy@...dia.com"
<ziy@...dia.com>, "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
"linux-mm@...ck.org" <linux-mm@...ck.org>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>, Brendan Jackman <jackmanb@...gle.com>
Subject: Re: Ask help about this patch c0cd6f557b90 "mm: page_alloc: fix
freelist movement during block conversion"
> -----Original Message-----
> From: Johannes Weiner <hannes@...xchg.org>
> Sent: Thursday, April 3, 2025 3:44 AM
> To: Carlos Song <carlos.song@....com>
> Cc: baolin.wang@...ux.alibaba.com; ying.huang@...el.com; vbabka@...e.cz;
> david@...hat.com; mgorman@...hsingularity.net; ziy@...dia.com;
> akpm@...ux-foundation.org; linux-mm@...ck.org;
> linux-kernel@...r.kernel.org; Brendan Jackman <jackmanb@...gle.com>
> Subject: [EXT] Re: Ask help about this patch c0cd6f557b90 "mm: page_alloc: fix
> freelist movement during block conversion"
>
> Caution: This is an external email. Please take care when clicking links or
> opening attachments. When in doubt, report the message using the 'Report this
> email' button
>
>
> Hi Carlos,
>
> On Wed, Apr 02, 2025 at 11:31:58AM +0000, Carlos Song wrote:
> > Hi, all
> >
> > I found a 300ms~600ms IRQ off when writing 1Gb data to storage device at
> I.MX7d SDB board at Linux-kernel-v6.14.
> > From this discussion I find the regression root cause:
> > https://lore/
> > .kernel.org%2Flinux-mm%2FCAJuCfpGajtAP8-kw5B5mKmhfyq6Pn67%2BPJgMj
> BeozW
> >
> -qzjQMkw%40mail.gmail.com%2FT%2F&data=05%7C02%7Ccarlos.song%40nxp
> .com%
> >
> 7Cd7694a8c3df242bbfafb08dd721eca68%7C686ea1d3bc2b4c6fa92cd99c5c301
> 635%
> >
> 7C0%7C0%7C638792198771816986%7CUnknown%7CTWFpbGZsb3d8eyJFbXB0
> eU1hcGkiO
> >
> nRydWUsIlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%
> >
> 3D%3D%7C0%7C%7C%7C&sdata=uLdowX74RLIC8Lwd0u9UGub1Lx7MI6YLT1e2
> ERF5VmY%3
> > D&reserved=0
>
> Thanks for the report!
>
> > 2. After add this patch: c0cd6f557b90 "mm: page_alloc: fix freelist movement
> during block conversion"
> > # tracer: irqsoff
> > #
> > # irqsoff latency trace v1.1.5 on 6.9.0-rc4-00116-gc0cd6f557b90 #
> > --------------------------------------------------------------------
> > # latency: 93635 us, #13758/13758, CPU#0 | (M:server VP:0, KP:0, SP:0 HP:0
> #P:2)
> > # -----------------
> > # | task: dd-764 (uid:0 nice:0 policy:0 rt_prio:0)
> > # -----------------
> > # => started at: _raw_spin_lock_irqsave
> > # => ended at: _raw_spin_unlock_irqrestore
> > #
> > #
> > # _------=> CPU#
> > # / _-----=> irqs-off/BH-disabled
> > # | / _----=> need-resched
> > # || / _---=> hardirq/softirq
> > # ||| / _--=> preempt-depth
> > # |||| / _-=> migrate-disable
> > # ||||| / delay
> > # cmd pid |||||| time | caller
> > # \ / |||||| \ | /
> > dd-764 0d.... 1us!: _raw_spin_lock_irqsave
> > dd-764 0d.... 206us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-764 0d.... 209us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-764 0d.... 210us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-764 0d.... 213us+: steal_suitable_fallback
> <-__rmqueue_pcplist
> > dd-764 0d.... 281us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-764 0d.... 282us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-764 0d.... 284us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-764 0d.... 286us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-764 0d.... 288us+: steal_suitable_fallback
> <-__rmqueue_pcplist
>
> This is the freelists being replenished with a loop over __rmqueue(). Two things
> stand out:
>
> 1. steal_suitable_fallback() is the expensive part. The patch in
> question made this slightly worse because stealability is checked
> up-front instead of just stealing optimistically like before. So
> the pages in the block are iterated twice. This can explain some of
> the issue, but not a 100x increase in lock hold time.
>
> 2. We're doing it *a lot*. And this is the likely culprit. Whereas
> before the patch, we'd steal whole buddies and their remainders,
> afterwards there is a lot more single page stealing when grabbing
> the whole block fails. This means __rmqueue_smallest() fails more
> often and we end up doing a lot more topdown fallback scans:
>
> > dd-767 0d.... 2043us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2045us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2047us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2049us+: try_to_claim_block
> <-__rmqueue_pcplist
> > dd-767 0d.... 2101us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2103us+: try_to_claim_block
> <-__rmqueue_pcplist
> > dd-767 0d.... 2181us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2184us+: try_to_claim_block
> <-__rmqueue_pcplist
> > dd-767 0d.... 2220us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2222us+: try_to_claim_block
> <-__rmqueue_pcplist
> > dd-767 0d.... 2304us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2306us+: try_to_claim_block
> <-__rmqueue_pcplist
> > dd-767 0d.... 2365us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2367us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2368us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2370us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2372us+: try_to_claim_block
> <-__rmqueue_pcplist
> > dd-767 0d.... 2434us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2436us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2438us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2442us : __mod_zone_page_state
> <-__rmqueue_pcplist
>
> The __mod_zone_page_state() is the successful allocation after attempting to
> steal a few different blocks. If this had succeeded, it would have replenished the
> native freelist and we'd see another
> __mod_zone_page_state() quickly. Alas it failed:
>
> > dd-767 0d.... 2445us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2446us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2448us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2450us+: try_to_claim_block
> <-__rmqueue_pcplist
> > dd-767 0d.... 2490us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2492us+: try_to_claim_block
> <-__rmqueue_pcplist
> > dd-767 0d.... 2548us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2550us+: try_to_claim_block
> <-__rmqueue_pcplist
> > dd-767 0d.... 2586us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2588us+: try_to_claim_block
> <-__rmqueue_pcplist
> > dd-767 0d.... 2652us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2654us+: try_to_claim_block
> <-__rmqueue_pcplist
> > dd-767 0d.... 2712us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2714us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2715us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2717us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2719us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2720us+: try_to_claim_block
> <-__rmqueue_pcplist
> > dd-767 0d.... 2778us : find_suitable_fallback
> <-__rmqueue_pcplist
> > dd-767 0d.... 2780us : __mod_zone_page_state
> <-__rmqueue_pcplist
>
> ... and we go through the whole fallback spiel for the next page.
>
> We can definitely do better. rmqueue_bulk() holds the zone->lock the entire
> time, which means nobody else can modify the freelists underneath us. Once
> block claiming has failed, there is no point in trying it again for the next page.
>
> In fact, the recent kernel test bot report [1] appears to be related to this. It
> points to c2f6ea38fc1b640aa7a2e155cc1c0410ff91afa2 ("mm:
> page_alloc: don't steal single pages from biggest buddy"), a patch that further
> forces bottom-up freelist scans if block stealing fails.
>
> Attached is a patch that has __rmqueue() remember which fallback level it had
> to stoop to in order to succeed; for the next page, it restarts the search from
> there.
>
> I cannot reproduce Carlos' setup, but testing with lru-file-mmap-read from the
> kernel test bot, it shows a stark difference:
>
> upstream patched
> real 0m8.939s 0m5.546s
> user 0m2.617s 0m2.528s
> sys 0m52.885s 0m30.183s
>
> Trace points confirm that try_to_reclaim_block() is called about two orders of
> magnitudes less than before.
>
> [1]
> https://lore.kern/
> el.org%2Fall%2F202503271547.fc08b188-lkp%40intel.com%2F&data=05%7C02
> %7Ccarlos.song%40nxp.com%7Cd7694a8c3df242bbfafb08dd721eca68%7C686e
> a1d3bc2b4c6fa92cd99c5c301635%7C0%7C0%7C638792198771844055%7CUnk
> nown%7CTWFpbGZsb3d8eyJFbXB0eU1hcGkiOnRydWUsIlYiOiIwLjAuMDAwMCIsI
> lAiOiJXaW4zMiIsIkFOIjoiTWFpbCIsIldUIjoyfQ%3D%3D%7C0%7C%7C%7C&sdata=
> DyKhob0zA5ujzeidYFYx9EdvvM5Kps3YDk94wsIfTG0%3D&reserved=0
>
Hi,
Thank you for your quick ack and help! After applied this patch, it improved well.
I apply this patch at this HEAD:
f0a16f536332 (tag: next-20250403, origin/master, origin/HEAD) Add linux-next specific files for 20250403
and do 10 times same test like what I have done before in IMX7D:
The IRQ off tracer shows the irq_off time 7~10ms. Is this what you expected?
#
# irqsoff latency trace v1.1.5 on 6.14.0-next-20250403-00003-gf9e8473ee91a
# --------------------------------------------------------------------
# latency: 8111 us, #4323/4323, CPU#0 | (M:NONE VP:0, KP:0, SP:0 HP:0 #P:2)
# -----------------
# | task: dd-820 (uid:0 nice:0 policy:0 rt_prio:0)
# -----------------
# => started at: __rmqueue_pcplist
# => ended at: _raw_spin_unlock_irqrestore
#
#
# _------=> CPU#
# / _-----=> irqs-off/BH-disabled
# | / _----=> need-resched
# || / _---=> hardirq/softirq
# ||| / _--=> preempt-depth
# |||| / _-=> migrate-disable
# ||||| / delay
# cmd pid |||||| time | caller
# \ / |||||| \ | /
dd-820 0d.... 1us : __rmqueue_pcplist
dd-820 0d.... 3us : _raw_spin_trylock <-__rmqueue_pcplist
dd-820 0d.... 7us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 11us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 13us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 15us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 17us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 19us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 21us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 23us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 25us : __mod_zone_page_state <-__rmqueue_pcplist
...
dd-820 0d.... 1326us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 1328us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 1330us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 1332us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 1334us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 1336us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 1337us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 1339us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 1341us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 1343us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 1345us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 1347us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 1349us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 1351us : __mod_zone_page_state <-__rmqueue_pcplist
...
dd-820 0d.... 1660us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 1662us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 1664us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 1666us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 1668us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 1670us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 1672us+: try_to_claim_block <-__rmqueue_pcplist
dd-820 0d.... 1727us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 1729us+: try_to_claim_block <-__rmqueue_pcplist
dd-820 0d.... 1806us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 1807us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 1809us+: try_to_claim_block <-__rmqueue_pcplist
dd-820 0d.... 1854us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 1856us+: try_to_claim_block <-__rmqueue_pcplist
dd-820 0d.... 1893us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 1895us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 1896us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 1898us+: try_to_claim_block <-__rmqueue_pcplist
dd-820 0d.... 1954us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 1956us+: try_to_claim_block <-__rmqueue_pcplist
dd-820 0d.... 2012us : find_suitable_fallback <-__rmqueue_pcplist
...
dd-820 0d.... 8077us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 8079us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 8081us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 8083us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 8084us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 8086us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 8088us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 8089us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 8091us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 8093us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 8095us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 8097us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 8098us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 8100us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 8102us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 8104us : find_suitable_fallback <-__rmqueue_pcplist
dd-820 0d.... 8105us : __mod_zone_page_state <-__rmqueue_pcplist
dd-820 0d.... 8107us : _raw_spin_unlock_irqrestore <-__rmqueue_pcplist
dd-820 0d.... 8110us : _raw_spin_unlock_irqrestore
dd-820 0d.... 8113us+: trace_hardirqs_on <-_raw_spin_unlock_irqrestore
dd-820 0d.... 8156us : <stack trace>
=> get_page_from_freelist
=> __alloc_frozen_pages_noprof
=> __folio_alloc_noprof
=> __filemap_get_folio
=> iomap_write_begin
=> iomap_file_buffered_write
=> blkdev_write_iter
=> vfs_write
=> ksys_write
=> ret_fast_syscall
Carlos Song
> ---
>
> From 13433454403e0c6f99ccc3b76c609034fe47e41c Mon Sep 17 00:00:00
> 2001
> From: Johannes Weiner <hannes@...xchg.org>
> Date: Wed, 2 Apr 2025 14:23:53 -0400
> Subject: [PATCH] mm: page_alloc: speed up fallbacks in rmqueue_bulk()
>
> Not-yet-signed-off-by: Johannes Weiner <hannes@...xchg.org>
> ---
> mm/page_alloc.c | 100 +++++++++++++++++++++++++++++++++++-------------
> 1 file changed, 74 insertions(+), 26 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c index
> f51aa6051a99..03b0d45ed45a 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2194,11 +2194,11 @@ try_to_claim_block(struct zone *zone, struct page
> *page,
> * The use of signed ints for order and current_order is a deliberate
> * deviation from the rest of this file, to make the for loop
> * condition simpler.
> - *
> - * Return the stolen page, or NULL if none can be found.
> */
> +
> +/* Try to claim a whole foreign block, take a page, expand the
> +remainder */
> static __always_inline struct page *
> -__rmqueue_fallback(struct zone *zone, int order, int start_migratetype,
> +__rmqueue_claim(struct zone *zone, int order, int start_migratetype,
> unsigned int
> alloc_flags) {
> struct free_area *area;
> @@ -2236,14 +2236,26 @@ __rmqueue_fallback(struct zone *zone, int order,
> int start_migratetype,
> page = try_to_claim_block(zone, page, current_order, order,
> start_migratetype,
> fallback_mt,
> alloc_flags);
> - if (page)
> - goto got_one;
> + if (page) {
> + trace_mm_page_alloc_extfrag(page, order,
> current_order,
> +
> start_migratetype, fallback_mt);
> + return page;
> + }
> }
>
> - if (alloc_flags & ALLOC_NOFRAGMENT)
> - return NULL;
> + return NULL;
> +}
> +
> +/* Try to steal a single page from a foreign block */ static
> +__always_inline struct page * __rmqueue_steal(struct zone *zone, int
> +order, int start_migratetype) {
> + struct free_area *area;
> + int current_order;
> + struct page *page;
> + int fallback_mt;
> + bool claim_block;
>
> - /* No luck claiming pageblock. Find the smallest fallback page */
> for (current_order = order; current_order < NR_PAGE_ORDERS;
> current_order++) {
> area = &(zone->free_area[current_order]);
> fallback_mt = find_suitable_fallback(area, current_order,
> @@ -2253,25 +2265,28 @@ __rmqueue_fallback(struct zone *zone, int order,
> int start_migratetype,
>
> page = get_page_from_free_area(area, fallback_mt);
> page_del_and_expand(zone, page, order, current_order,
> fallback_mt);
> - goto got_one;
> + trace_mm_page_alloc_extfrag(page, order, current_order,
> + start_migratetype,
> fallback_mt);
> + return page;
> }
>
> return NULL;
> -
> -got_one:
> - trace_mm_page_alloc_extfrag(page, order, current_order,
> - start_migratetype, fallback_mt);
> -
> - return page;
> }
>
> +enum rmqueue_mode {
> + RMQUEUE_NORMAL,
> + RMQUEUE_CMA,
> + RMQUEUE_CLAIM,
> + RMQUEUE_STEAL,
> +};
> +
> /*
> * Do the hard work of removing an element from the buddy allocator.
> * Call me with the zone->lock already held.
> */
> static __always_inline struct page *
> __rmqueue(struct zone *zone, unsigned int order, int migratetype,
> - unsigned int
> alloc_flags)
> + unsigned int alloc_flags, enum rmqueue_mode *mode)
> {
> struct page *page;
>
> @@ -2290,16 +2305,47 @@ __rmqueue(struct zone *zone, unsigned int order,
> int migratetype,
> }
> }
>
> - page = __rmqueue_smallest(zone, order, migratetype);
> - if (unlikely(!page)) {
> - if (alloc_flags & ALLOC_CMA)
> + /*
> + * Try the different freelists, native then foreign.
> + *
> + * The fallback logic is expensive and rmqueue_bulk() calls in
> + * a loop with the zone->lock held, meaning the freelists are
> + * not subject to any outside changes. Remember in *mode where
> + * we found pay dirt, to save us the search on the next call.
> + */
> + switch (*mode) {
> + case RMQUEUE_NORMAL:
> + page = __rmqueue_smallest(zone, order, migratetype);
> + if (page)
> + return page;
> + fallthrough;
> + case RMQUEUE_CMA:
> + if (alloc_flags & ALLOC_CMA) {
> page = __rmqueue_cma_fallback(zone, order);
> -
> - if (!page)
> - page = __rmqueue_fallback(zone, order,
> migratetype,
> - alloc_flags);
> + if (page) {
> + *mode = RMQUEUE_CMA;
> + return page;
> + }
> + }
> + fallthrough;
> + case RMQUEUE_CLAIM:
> + page = __rmqueue_claim(zone, order, migratetype,
> alloc_flags);
> + if (page) {
> + /* Replenished native freelist, back to normal
> mode */
> + *mode = RMQUEUE_NORMAL;
> + return page;
> + }
> + fallthrough;
> + case RMQUEUE_STEAL:
> + if (!(alloc_flags & ALLOC_NOFRAGMENT)) {
> + page = __rmqueue_steal(zone, order,
> migratetype);
> + if (page) {
> + *mode = RMQUEUE_STEAL;
> + return page;
> + }
> + }
> }
> - return page;
> + return NULL;
> }
>
> /*
> @@ -2311,6 +2357,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned
> int order,
> unsigned long count, struct list_head *list,
> int migratetype, unsigned int alloc_flags) {
> + enum rmqueue_mode rmqm = RMQUEUE_NORMAL;
> unsigned long flags;
> int i;
>
> @@ -2321,7 +2368,7 @@ static int rmqueue_bulk(struct zone *zone, unsigned
> int order,
> }
> for (i = 0; i < count; ++i) {
> struct page *page = __rmqueue(zone, order, migratetype,
> -
> alloc_flags);
> + alloc_flags, &rmqm);
> if (unlikely(page == NULL))
> break;
>
> @@ -2934,6 +2981,7 @@ struct page *rmqueue_buddy(struct zone
> *preferred_zone, struct zone *zone, {
> struct page *page;
> unsigned long flags;
> + enum rmqueue_mode rmqm = RMQUEUE_NORMAL;
>
> do {
> page = NULL;
> @@ -2945,7 +2993,7 @@ struct page *rmqueue_buddy(struct zone
> *preferred_zone, struct zone *zone,
> if (alloc_flags & ALLOC_HIGHATOMIC)
> page = __rmqueue_smallest(zone, order,
> MIGRATE_HIGHATOMIC);
> if (!page) {
> - page = __rmqueue(zone, order, migratetype,
> alloc_flags);
> + page = __rmqueue(zone, order, migratetype,
> + alloc_flags, &rmqm);
>
> /*
> * If the allocation fails, allow OOM handling and
> --
> 2.49.0
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