| Message ID | 1685501461-19290-1-git-send-email-zhaoyang.huang@unisoc.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [PATCHv5] mm: skip CMA pages when they are not available | expand |
On Wed, 31 May 2023 10:51:01 +0800 "zhaoyang.huang" <zhaoyang.huang@unisoc.com> wrote: > From: Zhaoyang Huang <zhaoyang.huang@unisoc.com> > > This patch fixes unproductive reclaiming of CMA pages by skipping them when they > are not available for current context. It is arise from bellowing OOM issue, which > caused by large proportion of MIGRATE_CMA pages among free pages. > > [ 36.172486] [03-19 10:05:52.172] ActivityManager: page allocation failure: order:0, mode:0xc00(GFP_NOIO), nodemask=(null),cpuset=foreground,mems_allowed=0 > [ 36.189447] [03-19 10:05:52.189] DMA32: 0*4kB 447*8kB (C) 217*16kB (C) 124*32kB (C) 136*64kB (C) 70*128kB (C) 22*256kB (C) 3*512kB (C) 0*1024kB 0*2048kB 0*4096kB = 35848kB > [ 36.193125] [03-19 10:05:52.193] Normal: 231*4kB (UMEH) 49*8kB (MEH) 14*16kB (H) 13*32kB (H) 8*64kB (H) 2*128kB (H) 0*256kB 1*512kB (H) 0*1024kB 0*2048kB 0*4096kB = 3236kB > ... > [ 36.234447] [03-19 10:05:52.234] SLUB: Unable to allocate memory on node -1, gfp=0xa20(GFP_ATOMIC) > [ 36.234455] [03-19 10:05:52.234] cache: ext4_io_end, object size: 64, buffer size: 64, default order: 0, min order: 0 > [ 36.234459] [03-19 10:05:52.234] node 0: slabs: 53,objs: 3392, free: 0 > We saw plenty of feedback for earlier versions, but now silence. Does this mean we're all OK with v5?
On Fri, Jun 09, 2023 at 03:35:19PM -0700, Andrew Morton wrote: > > This patch fixes unproductive reclaiming of CMA pages by skipping them when they > > are not available for current context. It is arise from bellowing OOM issue, which > > caused by large proportion of MIGRATE_CMA pages among free pages. > > We saw plenty of feedback for earlier versions, but now silence. Does > this mean we're all OK with v5? I'm fine with the implementation now. I have no idea if this is the right approach.
On 10.06.23 00:35, Andrew Morton wrote: > On Wed, 31 May 2023 10:51:01 +0800 "zhaoyang.huang" <zhaoyang.huang@unisoc.com> wrote: > >> From: Zhaoyang Huang <zhaoyang.huang@unisoc.com> >> >> This patch fixes unproductive reclaiming of CMA pages by skipping them when they >> are not available for current context. It is arise from bellowing OOM issue, which >> caused by large proportion of MIGRATE_CMA pages among free pages. >> >> [ 36.172486] [03-19 10:05:52.172] ActivityManager: page allocation failure: order:0, mode:0xc00(GFP_NOIO), nodemask=(null),cpuset=foreground,mems_allowed=0 >> [ 36.189447] [03-19 10:05:52.189] DMA32: 0*4kB 447*8kB (C) 217*16kB (C) 124*32kB (C) 136*64kB (C) 70*128kB (C) 22*256kB (C) 3*512kB (C) 0*1024kB 0*2048kB 0*4096kB = 35848kB >> [ 36.193125] [03-19 10:05:52.193] Normal: 231*4kB (UMEH) 49*8kB (MEH) 14*16kB (H) 13*32kB (H) 8*64kB (H) 2*128kB (H) 0*256kB 1*512kB (H) 0*1024kB 0*2048kB 0*4096kB = 3236kB >> ... >> [ 36.234447] [03-19 10:05:52.234] SLUB: Unable to allocate memory on node -1, gfp=0xa20(GFP_ATOMIC) >> [ 36.234455] [03-19 10:05:52.234] cache: ext4_io_end, object size: 64, buffer size: 64, default order: 0, min order: 0 >> [ 36.234459] [03-19 10:05:52.234] node 0: slabs: 53,objs: 3392, free: 0 >> > > We saw plenty of feedback for earlier versions, but now silence. Does > this mean we're all OK with v5? The logic kind-of makes sense to me (but the kswapd special-casing already shows that it might be a bit fragile for future use), but I did not yet figure out if this actually fixes something or is a pure performance improvement. As we phrased it in the comment "It is waste of effort", but in the patch description "This patch fixes unproductive reclaiming" + a scary dmesg. Am I correct that this is a pure performance optimization (and the issue revealed itself in that OOM report), or does this actually *fix* something? If it's a performance improvement, it would be good to show that it is an actual improvement worth the churn ...
On Mon, Jun 12, 2023 at 5:29 PM David Hildenbrand <david@redhat.com> wrote: > > On 10.06.23 00:35, Andrew Morton wrote: > > On Wed, 31 May 2023 10:51:01 +0800 "zhaoyang.huang" <zhaoyang.huang@unisoc.com> wrote: > > > >> From: Zhaoyang Huang <zhaoyang.huang@unisoc.com> > >> > >> This patch fixes unproductive reclaiming of CMA pages by skipping them when they > >> are not available for current context. It is arise from bellowing OOM issue, which > >> caused by large proportion of MIGRATE_CMA pages among free pages. > >> > >> [ 36.172486] [03-19 10:05:52.172] ActivityManager: page allocation failure: order:0, mode:0xc00(GFP_NOIO), nodemask=(null),cpuset=foreground,mems_allowed=0 > >> [ 36.189447] [03-19 10:05:52.189] DMA32: 0*4kB 447*8kB (C) 217*16kB (C) 124*32kB (C) 136*64kB (C) 70*128kB (C) 22*256kB (C) 3*512kB (C) 0*1024kB 0*2048kB 0*4096kB = 35848kB > >> [ 36.193125] [03-19 10:05:52.193] Normal: 231*4kB (UMEH) 49*8kB (MEH) 14*16kB (H) 13*32kB (H) 8*64kB (H) 2*128kB (H) 0*256kB 1*512kB (H) 0*1024kB 0*2048kB 0*4096kB = 3236kB > >> ... > >> [ 36.234447] [03-19 10:05:52.234] SLUB: Unable to allocate memory on node -1, gfp=0xa20(GFP_ATOMIC) > >> [ 36.234455] [03-19 10:05:52.234] cache: ext4_io_end, object size: 64, buffer size: 64, default order: 0, min order: 0 > >> [ 36.234459] [03-19 10:05:52.234] node 0: slabs: 53,objs: 3392, free: 0 > >> > > > > We saw plenty of feedback for earlier versions, but now silence. Does > > this mean we're all OK with v5? > > The logic kind-of makes sense to me (but the kswapd special-casing > already shows that it might be a bit fragile for future use), but I did > not yet figure out if this actually fixes something or is a pure > performance improvement. > > As we phrased it in the comment "It is waste of effort", but in the > patch description "This patch fixes unproductive reclaiming" + a scary > dmesg. > > Am I correct that this is a pure performance optimization (and the issue > revealed itself in that OOM report), or does this actually *fix* something? > > If it's a performance improvement, it would be good to show that it is > an actual improvement worth the churn ... Sorry for the confusion. As for the OOM issue, the previous commit(https://lkml.kernel.org/r/1683782550-25799-1-git-send-email-zhaoyang.huang@unisoc.com) helps to decrease the fail rate from 12/20 to 2/20, which it turn to be 0 when applying this patch. > > -- > Cheers, > > David / dhildenb >
On 12.06.23 11:35, Zhaoyang Huang wrote: > On Mon, Jun 12, 2023 at 5:29 PM David Hildenbrand <david@redhat.com> wrote: >> >> On 10.06.23 00:35, Andrew Morton wrote: >>> On Wed, 31 May 2023 10:51:01 +0800 "zhaoyang.huang" <zhaoyang.huang@unisoc.com> wrote: >>> >>>> From: Zhaoyang Huang <zhaoyang.huang@unisoc.com> >>>> >>>> This patch fixes unproductive reclaiming of CMA pages by skipping them when they >>>> are not available for current context. It is arise from bellowing OOM issue, which >>>> caused by large proportion of MIGRATE_CMA pages among free pages. >>>> >>>> [ 36.172486] [03-19 10:05:52.172] ActivityManager: page allocation failure: order:0, mode:0xc00(GFP_NOIO), nodemask=(null),cpuset=foreground,mems_allowed=0 >>>> [ 36.189447] [03-19 10:05:52.189] DMA32: 0*4kB 447*8kB (C) 217*16kB (C) 124*32kB (C) 136*64kB (C) 70*128kB (C) 22*256kB (C) 3*512kB (C) 0*1024kB 0*2048kB 0*4096kB = 35848kB >>>> [ 36.193125] [03-19 10:05:52.193] Normal: 231*4kB (UMEH) 49*8kB (MEH) 14*16kB (H) 13*32kB (H) 8*64kB (H) 2*128kB (H) 0*256kB 1*512kB (H) 0*1024kB 0*2048kB 0*4096kB = 3236kB >>>> ... >>>> [ 36.234447] [03-19 10:05:52.234] SLUB: Unable to allocate memory on node -1, gfp=0xa20(GFP_ATOMIC) >>>> [ 36.234455] [03-19 10:05:52.234] cache: ext4_io_end, object size: 64, buffer size: 64, default order: 0, min order: 0 >>>> [ 36.234459] [03-19 10:05:52.234] node 0: slabs: 53,objs: 3392, free: 0 >>>> >>> >>> We saw plenty of feedback for earlier versions, but now silence. Does >>> this mean we're all OK with v5? >> >> The logic kind-of makes sense to me (but the kswapd special-casing >> already shows that it might be a bit fragile for future use), but I did >> not yet figure out if this actually fixes something or is a pure >> performance improvement. >> >> As we phrased it in the comment "It is waste of effort", but in the >> patch description "This patch fixes unproductive reclaiming" + a scary >> dmesg. >> >> Am I correct that this is a pure performance optimization (and the issue >> revealed itself in that OOM report), or does this actually *fix* something? >> >> If it's a performance improvement, it would be good to show that it is >> an actual improvement worth the churn ... > Sorry for the confusion. As for the OOM issue, the previous > commit(https://lkml.kernel.org/r/1683782550-25799-1-git-send-email-zhaoyang.huang@unisoc.com) > helps to decrease the fail rate from 12/20 to 2/20, which it turn to > be 0 when applying this patch. Thanks! Can we make that clearer in the patch description? I'm struggling a bit my self to find the right words. Something like "This change further decreases the chance for wrong OOMs in the presence of a lot of CMA memory." ? In any case Acked-by: David Hildenbrand <david@redhat.com>
On Mon, 12 Jun 2023 12:01:20 +0200 David Hildenbrand <david@redhat.com> wrote: > ... > > >> > >> If it's a performance improvement, it would be good to show that it is > >> an actual improvement worth the churn ... > > Sorry for the confusion. As for the OOM issue, the previous > > commit(https://lkml.kernel.org/r/1683782550-25799-1-git-send-email-zhaoyang.huang@unisoc.com) > > helps to decrease the fail rate from 12/20 to 2/20, which it turn to > > be 0 when applying this patch. > > Thanks! Can we make that clearer in the patch description? I'm > struggling a bit my self to find the right words. > > Something like > > "This change further decreases the chance for wrong OOMs in the presence > of a lot of CMA memory." > Great, I added that. > > In any case > > Acked-by: David Hildenbrand <david@redhat.com> > And I'll move this patch into mm-stable.
diff --git a/mm/vmscan.c b/mm/vmscan.c index bd6637f..972a54d 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2193,6 +2193,25 @@ 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. * @@ -2239,7 +2258,8 @@ 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) { + if (folio_zonenum(folio) > sc->reclaim_idx || + skip_cma(folio, sc)) { nr_skipped[folio_zonenum(folio)] += nr_pages; move_to = &folios_skipped; goto move;