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Thu, 18 Sep 2025 02:57:25 +0000 (UTC) Date: Thu, 18 Sep 2025 10:57:22 +0800 From: Baoquan He To: "Uladzislau Rezki (Sony)" Cc: linux-mm@kvack.org, Andrew Morton , Michal Hocko , LKML Subject: Re: [PATCH v2 04/10] mm/vmalloc: Avoid cond_resched() when blocking is not permitted Message-ID: References: <20250915134041.151462-1-urezki@gmail.com> <20250915134041.151462-5-urezki@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250915134041.151462-5-urezki@gmail.com> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 8D634140007 X-Stat-Signature: 1jdjyr993zkm4by4wfembx6szixmqsti X-Rspam-User: X-HE-Tag: 1758164252-759561 X-HE-Meta: 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 rf8x6b7R 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 09/15/25 at 03:40pm, Uladzislau Rezki (Sony) wrote: > vm_area_alloc_pages() contains the only voluntary reschedule points > along vmalloc() allocation path. They are needed to ensure forward > progress on PREEMPT_NONE kernels under contention for vmap metadata > (e.g. alloc_vmap_area()). > > However, yielding should only be done if the given GFP flags allow > blocking. This patch avoids calling cond_resched() when allocation > context is non-blocking(GFP_ATOMIC, GFP_NOWAIT). > > Signed-off-by: Uladzislau Rezki (Sony) > --- > mm/vmalloc.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) Reviewed-by: Baoquan He > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 49a0f81930a8..b77e8be75f10 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -3633,7 +3633,9 @@ vm_area_alloc_pages(gfp_t gfp, int nid, > pages + nr_allocated); > > nr_allocated += nr; > - cond_resched(); > + > + if (gfpflags_allow_blocking(gfp)) > + cond_resched(); > > /* > * If zero or pages were obtained partly, > @@ -3675,7 +3677,9 @@ vm_area_alloc_pages(gfp_t gfp, int nid, > for (i = 0; i < (1U << order); i++) > pages[nr_allocated + i] = page + i; > > - cond_resched(); > + if (gfpflags_allow_blocking(gfp)) > + cond_resched(); > + > nr_allocated += 1U << order; > } > > -- > 2.47.3 >