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Mon, 15 Sep 2025 06:40:46 -0700 (PDT) From: "Uladzislau Rezki (Sony)" To: linux-mm@kvack.org, Andrew Morton Cc: Michal Hocko , Baoquan He , LKML , Uladzislau Rezki Subject: [PATCH v2 04/10] mm/vmalloc: Avoid cond_resched() when blocking is not permitted Date: Mon, 15 Sep 2025 15:40:34 +0200 Message-ID: <20250915134041.151462-5-urezki@gmail.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20250915134041.151462-1-urezki@gmail.com> References: <20250915134041.151462-1-urezki@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" 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) Acked-by: Michal Hocko Reviewed-by: Baoquan He --- mm/vmalloc.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) 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); =20 nr_allocated +=3D nr; - cond_resched(); + + if (gfpflags_allow_blocking(gfp)) + cond_resched(); =20 /* * If zero or pages were obtained partly, @@ -3675,7 +3677,9 @@ vm_area_alloc_pages(gfp_t gfp, int nid, for (i =3D 0; i < (1U << order); i++) pages[nr_allocated + i] =3D page + i; =20 - cond_resched(); + if (gfpflags_allow_blocking(gfp)) + cond_resched(); + nr_allocated +=3D 1U << order; } =20 --=20 2.47.3