mm/vmscan.c | 22 +--------------------- 1 file changed, 1 insertion(+), 21 deletions(-)
From: "Hailong.Liu" <liuhailong@oppo.com>
This reverts commit 5da226dbfce3a2f44978c2c7cf88166e69a6788b.
patch may cause system not responding. if cma pages is large in lru_list
and system is in lowmemory, many tasks would enter direct reclaim and waste
cpu time to isolate and return. Test this patch on android-5.15 device
and tasks call stack as below.
Task name: UsbFfs-worker [affinity: 0xff] pid: 3374 cpu: 7 prio: 120 start: ffffff8897a35c80
state: 0x0[R] exit_state: 0x0 stack base: 0xffffffc01eaa0000
Last_enqueued_ts: 0.000000000 Last_sleep_ts: 0.000000000
Stack:
[<ffffffd32ee7d910>] __switch_to+0x180
[<ffffffd3302022fc>] __schedule+0x4dc
[<ffffffd330201e08>] preempt_schedule+0x5c
[<ffffffd33020a4d0>] _raw_spin_unlock_irq+0x54
[<ffffffd32f14906c>] shrink_inactive_list+0x1d0
[<ffffffd32f143998>] shrink_lruvec+0x1bc
[<ffffffd32f147c0c>] shrink_node_memcgs+0x184
[<ffffffd32f147414>] shrink_node+0x2d0
[<ffffffd32f146d38>] shrink_zones+0x14c
[<ffffffd32f142e84>] do_try_to_free_pages+0xe8
[<ffffffd32f142b08>] try_to_free_pages+0x2e0
[<ffffffd32f1a8e44>] __alloc_pages_direct_reclaim+0x84
[<ffffffd32f1a2d58>] __alloc_pages_slowpath+0x4d0
[<ffffffd32f1a23bc>] __alloc_pages_nodemask[jt]+0x124
[<ffffffd32f19a220>] __vmalloc_area_node+0x188
[<ffffffd32f19a540>] __vmalloc_node+0x148
[<ffffffd32f19a60c>] vmalloc+0x4c
[<ffffffd32f910218>] ffs_epfile_io+0x258
[<ffffffd330033780>] kretprobe_trampoline[jt]+0x0
[<ffffffd330033780>] kretprobe_trampoline[jt]+0x0
[<ffffffd32f28129c>] __io_submit_one+0x1c0
[<ffffffd32f280e38>] io_submit_one+0x88
[<ffffffd32f280c88>] __do_sys_io_submit+0x178
[<ffffffd32f27eac0>] __arm64_sys_io_submit+0x20
[<ffffffd32eeabb74>] el0_svc_common.llvm.9961749221945255377+0xd0
[<ffffffd32eeaba34>] do_el0_svc+0x28
[<ffffffd32ff21be8>] el0_svc+0x14
[<ffffffd32ff21b70>] el0_sync_handler+0x88
[<ffffffd32ee128b8>] el0_sync+0x1b8
Task name: kthreadd [affinity: 0xff] pid: 2 cpu: 7 prio: 120 start: ffffff87808c0000
state: 0x0[R] exit_state: 0x0 stack base: 0xffffffc008078000
Last_enqueued_ts: 0.000000000 Last_sleep_ts: 0.000000000
Stack:
[<ffffffd32ee7d910>] __switch_to+0x180
[<ffffffd3302022fc>] __schedule+0x4dc
[<ffffffd330201e08>] preempt_schedule+0x5c
[<ffffffd33020a4d0>] _raw_spin_unlock_irq+0x54
[<ffffffd32f149168>] shrink_inactive_list+0x2cc
[<ffffffd32f143998>] shrink_lruvec+0x1bc
[<ffffffd32f147c0c>] shrink_node_memcgs+0x184
[<ffffffd32f147414>] shrink_node+0x2d0
[<ffffffd32f146d38>] shrink_zones+0x14c
[<ffffffd32f142e84>] do_try_to_free_pages+0xe8
[<ffffffd32f142b08>] try_to_free_pages+0x2e0
[<ffffffd32f1a8e44>] __alloc_pages_direct_reclaim+0x84
[<ffffffd32f1a2d58>] __alloc_pages_slowpath+0x4d0
[<ffffffd32f1a23bc>] __alloc_pages_nodemask[jt]+0x124
[<ffffffd32f19a220>] __vmalloc_area_node+0x188
[<ffffffd32f19a044>] __vmalloc_node_range+0x88
[<ffffffd32f0fb430>] scs_alloc+0x1b8
[<ffffffd32f0fb62c>] scs_prepare+0x20
[<ffffffd32ef2ce04>] dup_task_struct+0xd4
[<ffffffd32ef2a77c>] copy_process+0x144
[<ffffffd32ef2bae4>] kernel_clone+0xb4
[<ffffffd32ef2c040>] kernel_thread+0x5c
[<ffffffd32ef618d0>] kthreadd+0x184
without this patch, the tasks will reclaim cma pages and wakeup
oom-killer or not spin on cpus.
Signed-off-by: Hailong.Liu <liuhailong@oppo.com>
---
mm/vmscan.c | 22 +---------------------
1 file changed, 1 insertion(+), 21 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 2fe4a11d63f4..197ddf62019f 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2261,25 +2261,6 @@ static __always_inline void update_lru_sizes(struct lruvec *lruvec,
}
-#ifdef CONFIG_CMA
-/*
- * It is waste of effort to scan and reclaim CMA pages if it is not available
- * for current allocation context. Kswapd can not be enrolled as it can not
- * distinguish this scenario by using sc->gfp_mask = GFP_KERNEL
- */
-static bool skip_cma(struct folio *folio, struct scan_control *sc)
-{
- return !current_is_kswapd() &&
- gfp_migratetype(sc->gfp_mask) != MIGRATE_MOVABLE &&
- get_pageblock_migratetype(&folio->page) == MIGRATE_CMA;
-}
-#else
-static bool skip_cma(struct folio *folio, struct scan_control *sc)
-{
- return false;
-}
-#endif
-
/*
* Isolating page from the lruvec to fill in @dst list by nr_to_scan times.
*
@@ -2326,8 +2307,7 @@ static unsigned long isolate_lru_folios(unsigned long nr_to_scan,
nr_pages = folio_nr_pages(folio);
total_scan += nr_pages;
- if (folio_zonenum(folio) > sc->reclaim_idx ||
- skip_cma(folio, sc)) {
+ if (folio_zonenum(folio) > sc->reclaim_idx) {
nr_skipped[folio_zonenum(folio)] += nr_pages;
move_to = &folios_skipped;
goto move;
--
2.34.1On Thu, Mar 14, 2024 at 10:15 AM <liuhailong@oppo.com> wrote:
>
> From: "Hailong.Liu" <liuhailong@oppo.com>
>
> This reverts commit 5da226dbfce3a2f44978c2c7cf88166e69a6788b.
>
> patch may cause system not responding. if cma pages is large in lru_list
> and system is in lowmemory, many tasks would enter direct reclaim and waste
> cpu time to isolate and return. Test this patch on android-5.15 device
> and tasks call stack as below.
>
> Task name: UsbFfs-worker [affinity: 0xff] pid: 3374 cpu: 7 prio: 120 start: ffffff8897a35c80
> state: 0x0[R] exit_state: 0x0 stack base: 0xffffffc01eaa0000
> Last_enqueued_ts: 0.000000000 Last_sleep_ts: 0.000000000
> Stack:
> [<ffffffd32ee7d910>] __switch_to+0x180
> [<ffffffd3302022fc>] __schedule+0x4dc
> [<ffffffd330201e08>] preempt_schedule+0x5c
> [<ffffffd33020a4d0>] _raw_spin_unlock_irq+0x54
> [<ffffffd32f14906c>] shrink_inactive_list+0x1d0
> [<ffffffd32f143998>] shrink_lruvec+0x1bc
> [<ffffffd32f147c0c>] shrink_node_memcgs+0x184
> [<ffffffd32f147414>] shrink_node+0x2d0
> [<ffffffd32f146d38>] shrink_zones+0x14c
> [<ffffffd32f142e84>] do_try_to_free_pages+0xe8
> [<ffffffd32f142b08>] try_to_free_pages+0x2e0
> [<ffffffd32f1a8e44>] __alloc_pages_direct_reclaim+0x84
> [<ffffffd32f1a2d58>] __alloc_pages_slowpath+0x4d0
> [<ffffffd32f1a23bc>] __alloc_pages_nodemask[jt]+0x124
> [<ffffffd32f19a220>] __vmalloc_area_node+0x188
> [<ffffffd32f19a540>] __vmalloc_node+0x148
> [<ffffffd32f19a60c>] vmalloc+0x4c
> [<ffffffd32f910218>] ffs_epfile_io+0x258
> [<ffffffd330033780>] kretprobe_trampoline[jt]+0x0
> [<ffffffd330033780>] kretprobe_trampoline[jt]+0x0
> [<ffffffd32f28129c>] __io_submit_one+0x1c0
> [<ffffffd32f280e38>] io_submit_one+0x88
> [<ffffffd32f280c88>] __do_sys_io_submit+0x178
> [<ffffffd32f27eac0>] __arm64_sys_io_submit+0x20
> [<ffffffd32eeabb74>] el0_svc_common.llvm.9961749221945255377+0xd0
> [<ffffffd32eeaba34>] do_el0_svc+0x28
> [<ffffffd32ff21be8>] el0_svc+0x14
> [<ffffffd32ff21b70>] el0_sync_handler+0x88
> [<ffffffd32ee128b8>] el0_sync+0x1b8
>
> Task name: kthreadd [affinity: 0xff] pid: 2 cpu: 7 prio: 120 start: ffffff87808c0000
> state: 0x0[R] exit_state: 0x0 stack base: 0xffffffc008078000
> Last_enqueued_ts: 0.000000000 Last_sleep_ts: 0.000000000
> Stack:
> [<ffffffd32ee7d910>] __switch_to+0x180
> [<ffffffd3302022fc>] __schedule+0x4dc
> [<ffffffd330201e08>] preempt_schedule+0x5c
> [<ffffffd33020a4d0>] _raw_spin_unlock_irq+0x54
> [<ffffffd32f149168>] shrink_inactive_list+0x2cc
> [<ffffffd32f143998>] shrink_lruvec+0x1bc
> [<ffffffd32f147c0c>] shrink_node_memcgs+0x184
> [<ffffffd32f147414>] shrink_node+0x2d0
> [<ffffffd32f146d38>] shrink_zones+0x14c
> [<ffffffd32f142e84>] do_try_to_free_pages+0xe8
> [<ffffffd32f142b08>] try_to_free_pages+0x2e0
> [<ffffffd32f1a8e44>] __alloc_pages_direct_reclaim+0x84
> [<ffffffd32f1a2d58>] __alloc_pages_slowpath+0x4d0
> [<ffffffd32f1a23bc>] __alloc_pages_nodemask[jt]+0x124
> [<ffffffd32f19a220>] __vmalloc_area_node+0x188
> [<ffffffd32f19a044>] __vmalloc_node_range+0x88
> [<ffffffd32f0fb430>] scs_alloc+0x1b8
> [<ffffffd32f0fb62c>] scs_prepare+0x20
> [<ffffffd32ef2ce04>] dup_task_struct+0xd4
> [<ffffffd32ef2a77c>] copy_process+0x144
> [<ffffffd32ef2bae4>] kernel_clone+0xb4
> [<ffffffd32ef2c040>] kernel_thread+0x5c
> [<ffffffd32ef618d0>] kthreadd+0x184
>
> without this patch, the tasks will reclaim cma pages and wakeup
> oom-killer or not spin on cpus.
>
> Signed-off-by: Hailong.Liu <liuhailong@oppo.com>
> ---
> mm/vmscan.c | 22 +---------------------
> 1 file changed, 1 insertion(+), 21 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 2fe4a11d63f4..197ddf62019f 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2261,25 +2261,6 @@ static __always_inline void update_lru_sizes(struct lruvec *lruvec,
>
> }
>
> -#ifdef CONFIG_CMA
> -/*
> - * It is waste of effort to scan and reclaim CMA pages if it is not available
> - * for current allocation context. Kswapd can not be enrolled as it can not
> - * distinguish this scenario by using sc->gfp_mask = GFP_KERNEL
> - */
> -static bool skip_cma(struct folio *folio, struct scan_control *sc)
> -{
> - return !current_is_kswapd() &&
> - gfp_migratetype(sc->gfp_mask) != MIGRATE_MOVABLE &&
> - get_pageblock_migratetype(&folio->page) == MIGRATE_CMA;
> -}
> -#else
> -static bool skip_cma(struct folio *folio, struct scan_control *sc)
> -{
> - return false;
> -}
> -#endif
> -
NAK.
+Charan Teja Kalla -- This can cause build errors when CONFIG_LRU_GEN=y.
If you plan to post a v2, please include a reproducer. Thanks.
> /*
> * Isolating page from the lruvec to fill in @dst list by nr_to_scan times.
> *
> @@ -2326,8 +2307,7 @@ static unsigned long isolate_lru_folios(unsigned long nr_to_scan,
> nr_pages = folio_nr_pages(folio);
> total_scan += nr_pages;
>
> - if (folio_zonenum(folio) > sc->reclaim_idx ||
> - skip_cma(folio, sc)) {
> + if (folio_zonenum(folio) > sc->reclaim_idx) {
> nr_skipped[folio_zonenum(folio)] += nr_pages;
> move_to = &folios_skipped;
> goto move;
> --
> 2.34.1
>
>
On Thu, Mar 14, 2024 at 10:15 AM <liuhailong@oppo.com> wrote:
>
> From: "Hailong.Liu" <liuhailong@oppo.com>
>
> This reverts commit 5da226dbfce3a2f44978c2c7cf88166e69a6788b.
>
> patch may cause system not responding. if cma pages is large in lru_list
> and system is in lowmemory, many tasks would enter direct reclaim and waste
> cpu time to isolate and return. Test this patch on android-5.15 device
> and tasks call stack as below.
>
> Task name: UsbFfs-worker [affinity: 0xff] pid: 3374 cpu: 7 prio: 120 start: ffffff8897a35c80
> state: 0x0[R] exit_state: 0x0 stack base: 0xffffffc01eaa0000
> Last_enqueued_ts: 0.000000000 Last_sleep_ts: 0.000000000
> Stack:
> [<ffffffd32ee7d910>] __switch_to+0x180
> [<ffffffd3302022fc>] __schedule+0x4dc
> [<ffffffd330201e08>] preempt_schedule+0x5c
> [<ffffffd33020a4d0>] _raw_spin_unlock_irq+0x54
> [<ffffffd32f14906c>] shrink_inactive_list+0x1d0
> [<ffffffd32f143998>] shrink_lruvec+0x1bc
> [<ffffffd32f147c0c>] shrink_node_memcgs+0x184
> [<ffffffd32f147414>] shrink_node+0x2d0
> [<ffffffd32f146d38>] shrink_zones+0x14c
> [<ffffffd32f142e84>] do_try_to_free_pages+0xe8
> [<ffffffd32f142b08>] try_to_free_pages+0x2e0
> [<ffffffd32f1a8e44>] __alloc_pages_direct_reclaim+0x84
> [<ffffffd32f1a2d58>] __alloc_pages_slowpath+0x4d0
> [<ffffffd32f1a23bc>] __alloc_pages_nodemask[jt]+0x124
> [<ffffffd32f19a220>] __vmalloc_area_node+0x188
> [<ffffffd32f19a540>] __vmalloc_node+0x148
> [<ffffffd32f19a60c>] vmalloc+0x4c
> [<ffffffd32f910218>] ffs_epfile_io+0x258
> [<ffffffd330033780>] kretprobe_trampoline[jt]+0x0
> [<ffffffd330033780>] kretprobe_trampoline[jt]+0x0
> [<ffffffd32f28129c>] __io_submit_one+0x1c0
> [<ffffffd32f280e38>] io_submit_one+0x88
> [<ffffffd32f280c88>] __do_sys_io_submit+0x178
> [<ffffffd32f27eac0>] __arm64_sys_io_submit+0x20
> [<ffffffd32eeabb74>] el0_svc_common.llvm.9961749221945255377+0xd0
> [<ffffffd32eeaba34>] do_el0_svc+0x28
> [<ffffffd32ff21be8>] el0_svc+0x14
> [<ffffffd32ff21b70>] el0_sync_handler+0x88
> [<ffffffd32ee128b8>] el0_sync+0x1b8
>
> Task name: kthreadd [affinity: 0xff] pid: 2 cpu: 7 prio: 120 start: ffffff87808c0000
> state: 0x0[R] exit_state: 0x0 stack base: 0xffffffc008078000
> Last_enqueued_ts: 0.000000000 Last_sleep_ts: 0.000000000
> Stack:
> [<ffffffd32ee7d910>] __switch_to+0x180
> [<ffffffd3302022fc>] __schedule+0x4dc
> [<ffffffd330201e08>] preempt_schedule+0x5c
> [<ffffffd33020a4d0>] _raw_spin_unlock_irq+0x54
> [<ffffffd32f149168>] shrink_inactive_list+0x2cc
> [<ffffffd32f143998>] shrink_lruvec+0x1bc
> [<ffffffd32f147c0c>] shrink_node_memcgs+0x184
> [<ffffffd32f147414>] shrink_node+0x2d0
> [<ffffffd32f146d38>] shrink_zones+0x14c
> [<ffffffd32f142e84>] do_try_to_free_pages+0xe8
> [<ffffffd32f142b08>] try_to_free_pages+0x2e0
> [<ffffffd32f1a8e44>] __alloc_pages_direct_reclaim+0x84
> [<ffffffd32f1a2d58>] __alloc_pages_slowpath+0x4d0
> [<ffffffd32f1a23bc>] __alloc_pages_nodemask[jt]+0x124
> [<ffffffd32f19a220>] __vmalloc_area_node+0x188
> [<ffffffd32f19a044>] __vmalloc_node_range+0x88
> [<ffffffd32f0fb430>] scs_alloc+0x1b8
> [<ffffffd32f0fb62c>] scs_prepare+0x20
> [<ffffffd32ef2ce04>] dup_task_struct+0xd4
> [<ffffffd32ef2a77c>] copy_process+0x144
> [<ffffffd32ef2bae4>] kernel_clone+0xb4
> [<ffffffd32ef2c040>] kernel_thread+0x5c
> [<ffffffd32ef618d0>] kthreadd+0x184
>
> without this patch, the tasks will reclaim cma pages and wakeup
> oom-killer or not spin on cpus.
>
> Signed-off-by: Hailong.Liu <liuhailong@oppo.com>
> ---
> mm/vmscan.c | 22 +---------------------
> 1 file changed, 1 insertion(+), 21 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 2fe4a11d63f4..197ddf62019f 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2261,25 +2261,6 @@ static __always_inline void update_lru_sizes(struct lruvec *lruvec,
>
> }
>
> -#ifdef CONFIG_CMA
> -/*
> - * It is waste of effort to scan and reclaim CMA pages if it is not available
> - * for current allocation context. Kswapd can not be enrolled as it can not
> - * distinguish this scenario by using sc->gfp_mask = GFP_KERNEL
> - */
> -static bool skip_cma(struct folio *folio, struct scan_control *sc)
> -{
> - return !current_is_kswapd() &&
> - gfp_migratetype(sc->gfp_mask) != MIGRATE_MOVABLE &&
> - get_pageblock_migratetype(&folio->page) == MIGRATE_CMA;
> -}
> -#else
> -static bool skip_cma(struct folio *folio, struct scan_control *sc)
> -{
> - return false;
> -}
> -#endif
> -
>NAK.
>+Charan Teja Kalla -- This can cause build errors when CONFIG_LRU_GEN=y.
>If you plan to post a v2, please include a reproducer. Thanks.
Could you please retest the case with bellow patch, which has not been in the aosp yet.
From: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
According to current CMA utilization policy, an alloc_pages(GFP_USER)
could 'steal' UNMOVABLE & RECLAIMABLE page blocks via the help of
CMA(pass zone_watermark_ok by counting CMA in but use U&R in rmqueue),
which could lead to following alloc_pages(GFP_KERNEL) fail.
Solving this by introducing second watermark checking for GFP_MOVABLE,
which could have the allocation use CMA when proper.
-- Free_pages(30MB)
|
|
-- WMARK_LOW(25MB)
|
-- Free_CMA(12MB)
|
|
--
Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
---
v6: update comments
---
---
mm/page_alloc.c | 44 ++++++++++++++++++++++++++++++++++++++++----
1 file changed, 40 insertions(+), 4 deletions(-)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 452459836b71..5a146aa7c0aa 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2078,6 +2078,43 @@ __rmqueue_fallback(struct zone *zone, int order, int start_migratetype,
}
+#ifdef CONFIG_CMA
+/*
+ * GFP_MOVABLE allocation could drain UNMOVABLE & RECLAIMABLE page blocks via
+ * the help of CMA which makes GFP_KERNEL failed. Checking if zone_watermark_ok
+ * again without ALLOC_CMA to see if to use CMA first.
+ */
+static bool use_cma_first(struct zone *zone, unsigned int order, unsigned int alloc_flags)
+{
+ unsigned long watermark;
+ bool cma_first = false;
+
+ watermark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK);
+ /* check if GFP_MOVABLE pass previous zone_watermark_ok via the help of CMA */
+ if (zone_watermark_ok(zone, order, watermark, 0, alloc_flags & (~ALLOC_CMA))) {
+ /*
+ * Balance movable allocations between regular and CMA areas by
+ * allocating from CMA when over half of the zone's free memory
+ * is in the CMA area.
+ */
+ cma_first = (zone_page_state(zone, NR_FREE_CMA_PAGES) >
+ zone_page_state(zone, NR_FREE_PAGES) / 2);
+ } else {
+ /*
+ * watermark failed means UNMOVABLE & RECLAIMBLE is not enough
+ * now, we should use cma first to keep them stay around the
+ * corresponding watermark
+ */
+ cma_first = true;
+ }
+ return cma_first;
+}
+#else
+static bool use_cma_first(struct zone *zone, unsigned int order, unsigned int alloc_flags)
+{
+ return false;
+}
+#endif
/*
* Do the hard work of removing an element from the buddy allocator.
* Call me with the zone->lock already held.
@@ -2091,12 +2128,11 @@ __rmqueue(struct zone *zone, unsigned int order, int migratetype,
if (IS_ENABLED(CONFIG_CMA)) {
/*
* Balance movable allocations between regular and CMA areas by
- * allocating from CMA when over half of the zone's free memory
- * is in the CMA area.
+ * allocating from CMA base on judging zone_watermark_ok again
+ * to see if the latest check got pass via the help of CMA
*/
if (alloc_flags & ALLOC_CMA &&
- zone_page_state(zone, NR_FREE_CMA_PAGES) >
- zone_page_state(zone, NR_FREE_PAGES) / 2) {
+ use_cma_first(zone, order, alloc_flags)) {
page = __rmqueue_cma_fallback(zone, order);
if (page)
return page;
--
> /*
> * Isolating page from the lruvec to fill in @dst list by nr_to_scan times.
> *
> @@ -2326,8 +2307,7 @@ static unsigned long isolate_lru_folios(unsigned long nr_to_scan,
> nr_pages = folio_nr_pages(folio);
> total_scan += nr_pages;
>
> - if (folio_zonenum(folio) > sc->reclaim_idx ||
> - skip_cma(folio, sc)) {
> + if (folio_zonenum(folio) > sc->reclaim_idx) {
> nr_skipped[folio_zonenum(folio)] += nr_pages;
> move_to = &folios_skipped;
> goto move;
> --
> 2.34.1
>
>
On 2024/3/15 15:41, 黄朝阳 (Zhaoyang Huang) wrote:
>
>
> On Thu, Mar 14, 2024 at 10:15 AM <liuhailong@oppo.com> wrote:
>>
>> From: "Hailong.Liu" <liuhailong@oppo.com>
>>
>> This reverts commit 5da226dbfce3a2f44978c2c7cf88166e69a6788b.
>>
>> patch may cause system not responding. if cma pages is large in lru_list
>> and system is in lowmemory, many tasks would enter direct reclaim and waste
>> cpu time to isolate and return. Test this patch on android-5.15 device
>> and tasks call stack as below.
>>
>> Task name: UsbFfs-worker [affinity: 0xff] pid: 3374 cpu: 7 prio: 120 start: ffffff8897a35c80
>> state: 0x0[R] exit_state: 0x0 stack base: 0xffffffc01eaa0000
>> Last_enqueued_ts: 0.000000000 Last_sleep_ts: 0.000000000
>> Stack:
>> [<ffffffd32ee7d910>] __switch_to+0x180
>> [<ffffffd3302022fc>] __schedule+0x4dc
>> [<ffffffd330201e08>] preempt_schedule+0x5c
>> [<ffffffd33020a4d0>] _raw_spin_unlock_irq+0x54
>> [<ffffffd32f14906c>] shrink_inactive_list+0x1d0
>> [<ffffffd32f143998>] shrink_lruvec+0x1bc
>> [<ffffffd32f147c0c>] shrink_node_memcgs+0x184
>> [<ffffffd32f147414>] shrink_node+0x2d0
>> [<ffffffd32f146d38>] shrink_zones+0x14c
>> [<ffffffd32f142e84>] do_try_to_free_pages+0xe8
>> [<ffffffd32f142b08>] try_to_free_pages+0x2e0
>> [<ffffffd32f1a8e44>] __alloc_pages_direct_reclaim+0x84
>> [<ffffffd32f1a2d58>] __alloc_pages_slowpath+0x4d0
>> [<ffffffd32f1a23bc>] __alloc_pages_nodemask[jt]+0x124
>> [<ffffffd32f19a220>] __vmalloc_area_node+0x188
>> [<ffffffd32f19a540>] __vmalloc_node+0x148
>> [<ffffffd32f19a60c>] vmalloc+0x4c
>> [<ffffffd32f910218>] ffs_epfile_io+0x258
>> [<ffffffd330033780>] kretprobe_trampoline[jt]+0x0
>> [<ffffffd330033780>] kretprobe_trampoline[jt]+0x0
>> [<ffffffd32f28129c>] __io_submit_one+0x1c0
>> [<ffffffd32f280e38>] io_submit_one+0x88
>> [<ffffffd32f280c88>] __do_sys_io_submit+0x178
>> [<ffffffd32f27eac0>] __arm64_sys_io_submit+0x20
>> [<ffffffd32eeabb74>] el0_svc_common.llvm.9961749221945255377+0xd0
>> [<ffffffd32eeaba34>] do_el0_svc+0x28
>> [<ffffffd32ff21be8>] el0_svc+0x14
>> [<ffffffd32ff21b70>] el0_sync_handler+0x88
>> [<ffffffd32ee128b8>] el0_sync+0x1b8
>>
>> Task name: kthreadd [affinity: 0xff] pid: 2 cpu: 7 prio: 120 start: ffffff87808c0000
>> state: 0x0[R] exit_state: 0x0 stack base: 0xffffffc008078000
>> Last_enqueued_ts: 0.000000000 Last_sleep_ts: 0.000000000
>> Stack:
>> [<ffffffd32ee7d910>] __switch_to+0x180
>> [<ffffffd3302022fc>] __schedule+0x4dc
>> [<ffffffd330201e08>] preempt_schedule+0x5c
>> [<ffffffd33020a4d0>] _raw_spin_unlock_irq+0x54
>> [<ffffffd32f149168>] shrink_inactive_list+0x2cc
>> [<ffffffd32f143998>] shrink_lruvec+0x1bc
>> [<ffffffd32f147c0c>] shrink_node_memcgs+0x184
>> [<ffffffd32f147414>] shrink_node+0x2d0
>> [<ffffffd32f146d38>] shrink_zones+0x14c
>> [<ffffffd32f142e84>] do_try_to_free_pages+0xe8
>> [<ffffffd32f142b08>] try_to_free_pages+0x2e0
>> [<ffffffd32f1a8e44>] __alloc_pages_direct_reclaim+0x84
>> [<ffffffd32f1a2d58>] __alloc_pages_slowpath+0x4d0
>> [<ffffffd32f1a23bc>] __alloc_pages_nodemask[jt]+0x124
>> [<ffffffd32f19a220>] __vmalloc_area_node+0x188
>> [<ffffffd32f19a044>] __vmalloc_node_range+0x88
>> [<ffffffd32f0fb430>] scs_alloc+0x1b8
>> [<ffffffd32f0fb62c>] scs_prepare+0x20
>> [<ffffffd32ef2ce04>] dup_task_struct+0xd4
>> [<ffffffd32ef2a77c>] copy_process+0x144
>> [<ffffffd32ef2bae4>] kernel_clone+0xb4
>> [<ffffffd32ef2c040>] kernel_thread+0x5c
>> [<ffffffd32ef618d0>] kthreadd+0x184
>>
>> without this patch, the tasks will reclaim cma pages and wakeup
>> oom-killer or not spin on cpus.
>>
>> Signed-off-by: Hailong.Liu <liuhailong@oppo.com>
>> ---
>> mm/vmscan.c | 22 +---------------------
>> 1 file changed, 1 insertion(+), 21 deletions(-)
>>
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index 2fe4a11d63f4..197ddf62019f 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -2261,25 +2261,6 @@ static __always_inline void update_lru_sizes(struct lruvec *lruvec,
>>
>> }
>>
>> -#ifdef CONFIG_CMA
>> -/*
>> - * It is waste of effort to scan and reclaim CMA pages if it is not available
>> - * for current allocation context. Kswapd can not be enrolled as it can not
>> - * distinguish this scenario by using sc->gfp_mask = GFP_KERNEL
>> - */
>> -static bool skip_cma(struct folio *folio, struct scan_control *sc)
>> -{
>> - return !current_is_kswapd() &&
>> - gfp_migratetype(sc->gfp_mask) != MIGRATE_MOVABLE &&
>> - get_pageblock_migratetype(&folio->page) == MIGRATE_CMA;
>> -}
>> -#else
>> -static bool skip_cma(struct folio *folio, struct scan_control *sc)
>> -{
>> - return false;
>> -}
>> -#endif
>> -
>
>> NAK.
>
>> +Charan Teja Kalla -- This can cause build errors when CONFIG_LRU_GEN=y.
>
>> If you plan to post a v2, please include a reproducer. Thanks.
>
> Could you please retest the case with bellow patch, which has not been in the aosp yet.
>
> From: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
>
> According to current CMA utilization policy, an alloc_pages(GFP_USER)
> could 'steal' UNMOVABLE & RECLAIMABLE page blocks via the help of
> CMA(pass zone_watermark_ok by counting CMA in but use U&R in rmqueue),
> which could lead to following alloc_pages(GFP_KERNEL) fail.
> Solving this by introducing second watermark checking for GFP_MOVABLE,
> which could have the allocation use CMA when proper.
>
> -- Free_pages(30MB)
> |
> |
> -- WMARK_LOW(25MB)
> |
> -- Free_CMA(12MB)
> |
> |
> --
>
> Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
> ---
> v6: update comments
> ---
> ---
> mm/page_alloc.c | 44 ++++++++++++++++++++++++++++++++++++++++----
> 1 file changed, 40 insertions(+), 4 deletions(-)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 452459836b71..5a146aa7c0aa 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2078,6 +2078,43 @@ __rmqueue_fallback(struct zone *zone, int order, int start_migratetype,
>
> }
>
> +#ifdef CONFIG_CMA
> +/*
> + * GFP_MOVABLE allocation could drain UNMOVABLE & RECLAIMABLE page blocks via
> + * the help of CMA which makes GFP_KERNEL failed. Checking if zone_watermark_ok
> + * again without ALLOC_CMA to see if to use CMA first.
> + */
> +static bool use_cma_first(struct zone *zone, unsigned int order, unsigned int alloc_flags)
> +{
> + unsigned long watermark;
> + bool cma_first = false;
> +
> + watermark = wmark_pages(zone, alloc_flags & ALLOC_WMARK_MASK);
> + /* check if GFP_MOVABLE pass previous zone_watermark_ok via the help of CMA */
> + if (zone_watermark_ok(zone, order, watermark, 0, alloc_flags & (~ALLOC_CMA))) {
> + /*
> + * Balance movable allocations between regular and CMA areas by
> + * allocating from CMA when over half of the zone's free memory
> + * is in the CMA area.
> + */
> + cma_first = (zone_page_state(zone, NR_FREE_CMA_PAGES) >
> + zone_page_state(zone, NR_FREE_PAGES) / 2);
> + } else {
> + /*
> + * watermark failed means UNMOVABLE & RECLAIMBLE is not enough
> + * now, we should use cma first to keep them stay around the
> + * corresponding watermark
> + */
> + cma_first = true;
> + }
> + return cma_first;
> +}
> +#else
> +static bool use_cma_first(struct zone *zone, unsigned int order, unsigned int alloc_flags)
> +{
> + return false;
> +}
> +#endif
> /*
> * Do the hard work of removing an element from the buddy allocator.
> * Call me with the zone->lock already held.
> @@ -2091,12 +2128,11 @@ __rmqueue(struct zone *zone, unsigned int order, int migratetype,
> if (IS_ENABLED(CONFIG_CMA)) {
> /*
> * Balance movable allocations between regular and CMA areas by
> - * allocating from CMA when over half of the zone's free memory
> - * is in the CMA area.
> + * allocating from CMA base on judging zone_watermark_ok again
> + * to see if the latest check got pass via the help of CMA
> */
> if (alloc_flags & ALLOC_CMA &&
> - zone_page_state(zone, NR_FREE_CMA_PAGES) >
> - zone_page_state(zone, NR_FREE_PAGES) / 2) {
> + use_cma_first(zone, order, alloc_flags)) {
> page = __rmqueue_cma_fallback(zone, order);
> if (page)
> return page;
> --
>
Hi Zhaoyang:
I write a reproducer in v2-patch, this may not solve the case. because if
system in lowmemory all lru_list is cma pages. direct_reclaim would wasting time
scan and skip. For now we could not know how many cma pages in lru and do
some heuristic is something weird.
Brs,
Hailong.
From: "Hailong.Liu" <liuhailong@oppo.com>
This reverts
commit b7108d66318a ("Multi-gen LRU: skip CMA pages when they are not eligible")
commit 5da226dbfce3 ("mm: skip CMA pages when they are not available")
skip_cma may cause system not responding. if cma pages is large in lru_list
and system is in lowmemory, many tasks would direct reclaim and waste
cpu time to isolate_lru_pages and return.
Test this patch on android-5.15 8G device
reproducer:
- cma_declare_contiguous 3G pages
- set /proc/sys/vm/swappiness 0 to enable direct_reclaim reclaim file
only.
- run a memleak process in userspace
trace the trace_mm_vmscan_lru_isolate which get
[ 1178.059160] 2825 3405 I UsbFfs-worker : isolate_lru_pages:1895 total_scan: 24385 skipped: 24382
[ 1178.059699] 2825 3405 I UsbFfs-worker : isolate_lru_pages:1895 total_scan: 24412 skipped: 24401
[ 1178.061747] 2825 3405 I UsbFfs-worker : isolate_lru_pages:1895 total_scan: 24412 skipped: 24401
From the log, tasks is waste time to scan lru list and call stack as below.
Task name: UsbFfs-worker [affinity: 0xff] pid: 3374 cpu: 7 prio: 120 start: ffffff8897a35c80
state: 0x0[R] exit_state: 0x0 stack base: 0xffffffc01eaa0000
Last_enqueued_ts: 0.000000000 Last_sleep_ts: 0.000000000
Stack:
[<ffffffd32ee7d910>] __switch_to+0x180
[<ffffffd3302022fc>] __schedule+0x4dc
[<ffffffd330201e08>] preempt_schedule+0x5c
[<ffffffd33020a4d0>] _raw_spin_unlock_irq+0x54
[<ffffffd32f14906c>] shrink_inactive_list+0x1d0
[<ffffffd32f143998>] shrink_lruvec+0x1bc
[<ffffffd32f147c0c>] shrink_node_memcgs+0x184
[<ffffffd32f147414>] shrink_node+0x2d0
[<ffffffd32f146d38>] shrink_zones+0x14c
[<ffffffd32f142e84>] do_try_to_free_pages+0xe8
[<ffffffd32f142b08>] try_to_free_pages+0x2e0
[<ffffffd32f1a8e44>] __alloc_pages_direct_reclaim+0x84
[<ffffffd32f1a2d58>] __alloc_pages_slowpath+0x4d0
[<ffffffd32f1a23bc>] __alloc_pages_nodemask[jt]+0x124
[<ffffffd32f19a220>] __vmalloc_area_node+0x188
[<ffffffd32f19a540>] __vmalloc_node+0x148
[<ffffffd32f19a60c>] vmalloc+0x4c
[<ffffffd32f910218>] ffs_epfile_io+0x258
[<ffffffd330033780>] kretprobe_trampoline[jt]+0x0
[<ffffffd330033780>] kretprobe_trampoline[jt]+0x0
[<ffffffd32f28129c>] __io_submit_one+0x1c0
[<ffffffd32f280e38>] io_submit_one+0x88
[<ffffffd32f280c88>] __do_sys_io_submit+0x178
[<ffffffd32f27eac0>] __arm64_sys_io_submit+0x20
[<ffffffd32eeabb74>] el0_svc_common.llvm.9961749221945255377+0xd0
[<ffffffd32eeaba34>] do_el0_svc+0x28
[<ffffffd32ff21be8>] el0_svc+0x14
[<ffffffd32ff21b70>] el0_sync_handler+0x88
[<ffffffd32ee128b8>] el0_sync+0x1b8
Task name: kthreadd [affinity: 0xff] pid: 2 cpu: 7 prio: 120 start: ffffff87808c0000
state: 0x0[R] exit_state: 0x0 stack base: 0xffffffc008078000
Last_enqueued_ts: 0.000000000 Last_sleep_ts: 0.000000000
Stack:
[<ffffffd32ee7d910>] __switch_to+0x180
[<ffffffd3302022fc>] __schedule+0x4dc
[<ffffffd330201e08>] preempt_schedule+0x5c
[<ffffffd33020a4d0>] _raw_spin_unlock_irq+0x54
[<ffffffd32f149168>] shrink_inactive_list+0x2cc
[<ffffffd32f143998>] shrink_lruvec+0x1bc
[<ffffffd32f147c0c>] shrink_node_memcgs+0x184
[<ffffffd32f147414>] shrink_node+0x2d0
[<ffffffd32f146d38>] shrink_zones+0x14c
[<ffffffd32f142e84>] do_try_to_free_pages+0xe8
[<ffffffd32f142b08>] try_to_free_pages+0x2e0
[<ffffffd32f1a8e44>] __alloc_pages_direct_reclaim+0x84
[<ffffffd32f1a2d58>] __alloc_pages_slowpath+0x4d0
[<ffffffd32f1a23bc>] __alloc_pages_nodemask[jt]+0x124
[<ffffffd32f19a220>] __vmalloc_area_node+0x188
[<ffffffd32f19a044>] __vmalloc_node_range+0x88
[<ffffffd32f0fb430>] scs_alloc+0x1b8
[<ffffffd32f0fb62c>] scs_prepare+0x20
[<ffffffd32ef2ce04>] dup_task_struct+0xd4
[<ffffffd32ef2a77c>] copy_process+0x144
[<ffffffd32ef2bae4>] kernel_clone+0xb4
[<ffffffd32ef2c040>] kernel_thread+0x5c
[<ffffffd32ef618d0>] kthreadd+0x184
Signed-off-by: Hailong.Liu <liuhailong@oppo.com>
---
mm/vmscan.c | 24 ++----------------------
1 file changed, 2 insertions(+), 22 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 6f13394b112e..29306c29309f 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2261,25 +2261,6 @@ static __always_inline void update_lru_sizes(struct lruvec *lruvec,
}
-#ifdef CONFIG_CMA
-/*
- * It is waste of effort to scan and reclaim CMA pages if it is not available
- * for current allocation context. Kswapd can not be enrolled as it can not
- * distinguish this scenario by using sc->gfp_mask = GFP_KERNEL
- */
-static bool skip_cma(struct folio *folio, struct scan_control *sc)
-{
- return !current_is_kswapd() &&
- gfp_migratetype(sc->gfp_mask) != MIGRATE_MOVABLE &&
- get_pageblock_migratetype(&folio->page) == MIGRATE_CMA;
-}
-#else
-static bool skip_cma(struct folio *folio, struct scan_control *sc)
-{
- return false;
-}
-#endif
-
/*
* Isolating page from the lruvec to fill in @dst list by nr_to_scan times.
*
@@ -2326,8 +2307,7 @@ static unsigned long isolate_lru_folios(unsigned long nr_to_scan,
nr_pages = folio_nr_pages(folio);
total_scan += nr_pages;
- if (folio_zonenum(folio) > sc->reclaim_idx ||
- skip_cma(folio, sc)) {
+ if (folio_zonenum(folio) > sc->reclaim_idx) {
nr_skipped[folio_zonenum(folio)] += nr_pages;
move_to = &folios_skipped;
goto move;
@@ -4945,7 +4925,7 @@ static bool sort_folio(struct lruvec *lruvec, struct folio *folio, struct scan_c
}
/* ineligible */
- if (zone > sc->reclaim_idx || skip_cma(folio, sc)) {
+ if (zone > sc->reclaim_idx) {
gen = folio_inc_gen(lruvec, folio, false);
list_move_tail(&folio->lru, &lrugen->folios[gen][type][zone]);
return true;
--
Changes in v2:
- add reproducer
- fix build error on v6.6-rc7On Fri 15-03-24 16:18:03, liuhailong@oppo.com wrote:
> From: "Hailong.Liu" <liuhailong@oppo.com>
>
> This reverts
> commit b7108d66318a ("Multi-gen LRU: skip CMA pages when they are not eligible")
> commit 5da226dbfce3 ("mm: skip CMA pages when they are not available")
>
> skip_cma may cause system not responding. if cma pages is large in lru_list
> and system is in lowmemory, many tasks would direct reclaim and waste
> cpu time to isolate_lru_pages and return.
>
> Test this patch on android-5.15 8G device
> reproducer:
> - cma_declare_contiguous 3G pages
> - set /proc/sys/vm/swappiness 0 to enable direct_reclaim reclaim file
> only.
> - run a memleak process in userspace
Does this represent a sane configuration? CMA memory is unusable for
kernel allocations and memleak process is also hard to reclaim due to
swap suppression. Isn't such a system doomed to struggle to reclaim any
memory? Btw. how does the same setup behave with the regular LRU
implementation? My guess would be that it would struggle as well.
--
Michal Hocko
SUSE Labs
On Tue, Mar 19, 2024 at 4:56 PM Michal Hocko <mhocko@suse.com> wrote:
>
> On Fri 15-03-24 16:18:03, liuhailong@oppo.com wrote:
> > From: "Hailong.Liu" <liuhailong@oppo.com>
> >
> > This reverts
> > commit b7108d66318a ("Multi-gen LRU: skip CMA pages when they are not eligible")
> > commit 5da226dbfce3 ("mm: skip CMA pages when they are not available")
> >
> > skip_cma may cause system not responding. if cma pages is large in lru_list
> > and system is in lowmemory, many tasks would direct reclaim and waste
> > cpu time to isolate_lru_pages and return.
> >
> > Test this patch on android-5.15 8G device
> > reproducer:
> > - cma_declare_contiguous 3G pages
> > - set /proc/sys/vm/swappiness 0 to enable direct_reclaim reclaim file
> > only.
> > - run a memleak process in userspace
>
> Does this represent a sane configuration? CMA memory is unusable for
> kernel allocations and memleak process is also hard to reclaim due to
> swap suppression. Isn't such a system doomed to struggle to reclaim any
> memory? Btw. how does the same setup behave with the regular LRU
> implementation? My guess would be that it would struggle as well.
I assume the regular LRU implementation you are talking about is the LRU
without skip_cma()?
I remember Hailong mentioned something like " it also trigger memory psi
event to allow admin do something to release memory" and " without
patch the devices would kill camera process". So it seems the difference
is if a killing will occur.
Hailong, would you like to provide more detail?
> --
> Michal Hocko
> SUSE Labs
>
On Tue 19-03-24 19:09:18, Barry Song wrote:
> On Tue, Mar 19, 2024 at 4:56 PM Michal Hocko <mhocko@suse.com> wrote:
> >
> > On Fri 15-03-24 16:18:03, liuhailong@oppo.com wrote:
> > > From: "Hailong.Liu" <liuhailong@oppo.com>
> > >
> > > This reverts
> > > commit b7108d66318a ("Multi-gen LRU: skip CMA pages when they are not eligible")
> > > commit 5da226dbfce3 ("mm: skip CMA pages when they are not available")
> > >
> > > skip_cma may cause system not responding. if cma pages is large in lru_list
> > > and system is in lowmemory, many tasks would direct reclaim and waste
> > > cpu time to isolate_lru_pages and return.
> > >
> > > Test this patch on android-5.15 8G device
> > > reproducer:
> > > - cma_declare_contiguous 3G pages
> > > - set /proc/sys/vm/swappiness 0 to enable direct_reclaim reclaim file
> > > only.
> > > - run a memleak process in userspace
> >
> > Does this represent a sane configuration? CMA memory is unusable for
> > kernel allocations and memleak process is also hard to reclaim due to
> > swap suppression. Isn't such a system doomed to struggle to reclaim any
> > memory? Btw. how does the same setup behave with the regular LRU
> > implementation? My guess would be that it would struggle as well.
>
> I assume the regular LRU implementation you are talking about is the LRU
> without skip_cma()?
No, I mean standard LRU reclaim implementation rather than MGLRU.
--
Michal Hocko
SUSE Labs
On Wed, Mar 20, 2024 at 2:40 AM Michal Hocko <mhocko@suse.com> wrote:
>
> On Tue 19-03-24 19:09:18, Barry Song wrote:
> > On Tue, Mar 19, 2024 at 4:56 PM Michal Hocko <mhocko@suse.com> wrote:
> > >
> > > On Fri 15-03-24 16:18:03, liuhailong@oppo.com wrote:
> > > > From: "Hailong.Liu" <liuhailong@oppo.com>
> > > >
> > > > This reverts
> > > > commit b7108d66318a ("Multi-gen LRU: skip CMA pages when they are not eligible")
> > > > commit 5da226dbfce3 ("mm: skip CMA pages when they are not available")
> > > >
> > > > skip_cma may cause system not responding. if cma pages is large in lru_list
> > > > and system is in lowmemory, many tasks would direct reclaim and waste
> > > > cpu time to isolate_lru_pages and return.
> > > >
> > > > Test this patch on android-5.15 8G device
> > > > reproducer:
> > > > - cma_declare_contiguous 3G pages
> > > > - set /proc/sys/vm/swappiness 0 to enable direct_reclaim reclaim file
> > > > only.
> > > > - run a memleak process in userspace
> > >
> > > Does this represent a sane configuration? CMA memory is unusable for
> > > kernel allocations and memleak process is also hard to reclaim due to
> > > swap suppression. Isn't such a system doomed to struggle to reclaim any
> > > memory? Btw. how does the same setup behave with the regular LRU
> > > implementation? My guess would be that it would struggle as well.
> >
> > I assume the regular LRU implementation you are talking about is the LRU
> > without skip_cma()?
>
> No, I mean standard LRU reclaim implementation rather than MGLRU.
I guess Hailong was running the standard LRU with active/inactive lists
as his v1 even didn't touch MGLRU,
https://lore.kernel.org/linux-mm/20240314141516.31747-1-liuhailong@oppo.com/
Hailong, please correct me if this is not the case.
>
> --
> Michal Hocko
> SUSE Labs
On Fri, Mar 15, 2024 at 9:18 PM <liuhailong@oppo.com> wrote:
>
> From: "Hailong.Liu" <liuhailong@oppo.com>
>
> This reverts
> commit b7108d66318a ("Multi-gen LRU: skip CMA pages when they are not eligible")
> commit 5da226dbfce3 ("mm: skip CMA pages when they are not available")
Reverting these changes seems inappropriate since the original patches
did improve most cases.
While doing direct reclamation without MOVABLE flags, scanning cma
folio doesn't help at all.
>
> skip_cma may cause system not responding. if cma pages is large in lru_list
> and system is in lowmemory, many tasks would direct reclaim and waste
> cpu time to isolate_lru_pages and return.
>
> Test this patch on android-5.15 8G device
> reproducer:
> - cma_declare_contiguous 3G pages
> - set /proc/sys/vm/swappiness 0 to enable direct_reclaim reclaim file
> only.
> - run a memleak process in userspace
I assume that scanning cma folio provides additional opportunities to reclaim
anonymous memory, even though it is ineffective for allocating NON-MOVABLE
folios. Consequently, we alleviate pressure for future allocations of anonymous
folios. Moreover, setting swappiness=0 is a rare scenario. Instead of entirely
removing the mechanism, could we detect such corner cases and handle them
differently.
Otherwise, I don't see any chance of this being acknowledged.
>
> trace the trace_mm_vmscan_lru_isolate which get
> [ 1178.059160] 2825 3405 I UsbFfs-worker : isolate_lru_pages:1895 total_scan: 24385 skipped: 24382
> [ 1178.059699] 2825 3405 I UsbFfs-worker : isolate_lru_pages:1895 total_scan: 24412 skipped: 24401
> [ 1178.061747] 2825 3405 I UsbFfs-worker : isolate_lru_pages:1895 total_scan: 24412 skipped: 24401
> From the log, tasks is waste time to scan lru list and call stack as below.
>
> Task name: UsbFfs-worker [affinity: 0xff] pid: 3374 cpu: 7 prio: 120 start: ffffff8897a35c80
> state: 0x0[R] exit_state: 0x0 stack base: 0xffffffc01eaa0000
> Last_enqueued_ts: 0.000000000 Last_sleep_ts: 0.000000000
> Stack:
> [<ffffffd32ee7d910>] __switch_to+0x180
> [<ffffffd3302022fc>] __schedule+0x4dc
> [<ffffffd330201e08>] preempt_schedule+0x5c
> [<ffffffd33020a4d0>] _raw_spin_unlock_irq+0x54
> [<ffffffd32f14906c>] shrink_inactive_list+0x1d0
> [<ffffffd32f143998>] shrink_lruvec+0x1bc
> [<ffffffd32f147c0c>] shrink_node_memcgs+0x184
> [<ffffffd32f147414>] shrink_node+0x2d0
> [<ffffffd32f146d38>] shrink_zones+0x14c
> [<ffffffd32f142e84>] do_try_to_free_pages+0xe8
> [<ffffffd32f142b08>] try_to_free_pages+0x2e0
> [<ffffffd32f1a8e44>] __alloc_pages_direct_reclaim+0x84
> [<ffffffd32f1a2d58>] __alloc_pages_slowpath+0x4d0
> [<ffffffd32f1a23bc>] __alloc_pages_nodemask[jt]+0x124
> [<ffffffd32f19a220>] __vmalloc_area_node+0x188
> [<ffffffd32f19a540>] __vmalloc_node+0x148
> [<ffffffd32f19a60c>] vmalloc+0x4c
> [<ffffffd32f910218>] ffs_epfile_io+0x258
> [<ffffffd330033780>] kretprobe_trampoline[jt]+0x0
> [<ffffffd330033780>] kretprobe_trampoline[jt]+0x0
> [<ffffffd32f28129c>] __io_submit_one+0x1c0
> [<ffffffd32f280e38>] io_submit_one+0x88
> [<ffffffd32f280c88>] __do_sys_io_submit+0x178
> [<ffffffd32f27eac0>] __arm64_sys_io_submit+0x20
> [<ffffffd32eeabb74>] el0_svc_common.llvm.9961749221945255377+0xd0
> [<ffffffd32eeaba34>] do_el0_svc+0x28
> [<ffffffd32ff21be8>] el0_svc+0x14
> [<ffffffd32ff21b70>] el0_sync_handler+0x88
> [<ffffffd32ee128b8>] el0_sync+0x1b8
>
> Task name: kthreadd [affinity: 0xff] pid: 2 cpu: 7 prio: 120 start: ffffff87808c0000
> state: 0x0[R] exit_state: 0x0 stack base: 0xffffffc008078000
> Last_enqueued_ts: 0.000000000 Last_sleep_ts: 0.000000000
> Stack:
> [<ffffffd32ee7d910>] __switch_to+0x180
> [<ffffffd3302022fc>] __schedule+0x4dc
> [<ffffffd330201e08>] preempt_schedule+0x5c
> [<ffffffd33020a4d0>] _raw_spin_unlock_irq+0x54
> [<ffffffd32f149168>] shrink_inactive_list+0x2cc
> [<ffffffd32f143998>] shrink_lruvec+0x1bc
> [<ffffffd32f147c0c>] shrink_node_memcgs+0x184
> [<ffffffd32f147414>] shrink_node+0x2d0
> [<ffffffd32f146d38>] shrink_zones+0x14c
> [<ffffffd32f142e84>] do_try_to_free_pages+0xe8
> [<ffffffd32f142b08>] try_to_free_pages+0x2e0
> [<ffffffd32f1a8e44>] __alloc_pages_direct_reclaim+0x84
> [<ffffffd32f1a2d58>] __alloc_pages_slowpath+0x4d0
> [<ffffffd32f1a23bc>] __alloc_pages_nodemask[jt]+0x124
> [<ffffffd32f19a220>] __vmalloc_area_node+0x188
> [<ffffffd32f19a044>] __vmalloc_node_range+0x88
> [<ffffffd32f0fb430>] scs_alloc+0x1b8
> [<ffffffd32f0fb62c>] scs_prepare+0x20
> [<ffffffd32ef2ce04>] dup_task_struct+0xd4
> [<ffffffd32ef2a77c>] copy_process+0x144
> [<ffffffd32ef2bae4>] kernel_clone+0xb4
> [<ffffffd32ef2c040>] kernel_thread+0x5c
> [<ffffffd32ef618d0>] kthreadd+0x184
>
> Signed-off-by: Hailong.Liu <liuhailong@oppo.com>
> ---
> mm/vmscan.c | 24 ++----------------------
> 1 file changed, 2 insertions(+), 22 deletions(-)
>
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 6f13394b112e..29306c29309f 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2261,25 +2261,6 @@ static __always_inline void update_lru_sizes(struct lruvec *lruvec,
>
> }
>
> -#ifdef CONFIG_CMA
> -/*
> - * It is waste of effort to scan and reclaim CMA pages if it is not available
> - * for current allocation context. Kswapd can not be enrolled as it can not
> - * distinguish this scenario by using sc->gfp_mask = GFP_KERNEL
> - */
> -static bool skip_cma(struct folio *folio, struct scan_control *sc)
> -{
> - return !current_is_kswapd() &&
> - gfp_migratetype(sc->gfp_mask) != MIGRATE_MOVABLE &&
> - get_pageblock_migratetype(&folio->page) == MIGRATE_CMA;
> -}
> -#else
> -static bool skip_cma(struct folio *folio, struct scan_control *sc)
> -{
> - return false;
> -}
> -#endif
> -
> /*
> * Isolating page from the lruvec to fill in @dst list by nr_to_scan times.
> *
> @@ -2326,8 +2307,7 @@ static unsigned long isolate_lru_folios(unsigned long nr_to_scan,
> nr_pages = folio_nr_pages(folio);
> total_scan += nr_pages;
>
> - if (folio_zonenum(folio) > sc->reclaim_idx ||
> - skip_cma(folio, sc)) {
> + if (folio_zonenum(folio) > sc->reclaim_idx) {
> nr_skipped[folio_zonenum(folio)] += nr_pages;
> move_to = &folios_skipped;
> goto move;
> @@ -4945,7 +4925,7 @@ static bool sort_folio(struct lruvec *lruvec, struct folio *folio, struct scan_c
> }
>
> /* ineligible */
> - if (zone > sc->reclaim_idx || skip_cma(folio, sc)) {
> + if (zone > sc->reclaim_idx) {
> gen = folio_inc_gen(lruvec, folio, false);
> list_move_tail(&folio->lru, &lrugen->folios[gen][type][zone]);
> return true;
> --
> Changes in v2:
> - add reproducer
> - fix build error on v6.6-rc7
>
>
Thanks
Barry
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