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Fri, 04 Jul 2025 08:25:40 -0700 (PDT) From: "Uladzislau Rezki (Sony)" To: linux-mm@kvack.org, Andrew Morton Cc: Michal Hocko , LKML , Baoquan He , Uladzislau Rezki Subject: [RFC 2/7] mm/vmalloc: Support non-blocking GFP flags in alloc_vmap_area() Date: Fri, 4 Jul 2025 17:25:32 +0200 Message-Id: <20250704152537.55724-3-urezki@gmail.com> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250704152537.55724-1-urezki@gmail.com> References: <20250704152537.55724-1-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: 8bit alloc_vmap_area() currently assumes that sleeping is allowed during allocation. This is not true for callers which pass non-blocking GFP flags, such as GFP_ATOMIC or GFP_NOWAIT. This patch adds logic to detect whether the given gfp_mask permits blocking. It avoids invoking might_sleep() or falling back to reclaim path if blocking is not allowed. This makes alloc_vmap_area() safer for use in non-sleeping contexts, where previously it could hit unexpected sleeps, trigger warnings. Signed-off-by: Uladzislau Rezki (Sony) --- mm/vmalloc.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index ab986dd09b6a..8c375b8e269d 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2009,6 +2009,7 @@ static struct vmap_area *alloc_vmap_area(unsigned long size, unsigned long freed; unsigned long addr; unsigned int vn_id; + bool allow_block; int purged = 0; int ret; @@ -2018,7 +2019,9 @@ static struct vmap_area *alloc_vmap_area(unsigned long size, if (unlikely(!vmap_initialized)) return ERR_PTR(-EBUSY); - might_sleep(); + allow_block = gfpflags_allow_blocking(gfp_mask); + if (allow_block) + might_sleep(); /* * If a VA is obtained from a global heap(if it fails here) @@ -2030,7 +2033,8 @@ static struct vmap_area *alloc_vmap_area(unsigned long size, */ va = node_alloc(size, align, vstart, vend, &addr, &vn_id); if (!va) { - gfp_mask = gfp_mask & GFP_RECLAIM_MASK; + if (allow_block) + gfp_mask = gfp_mask & GFP_RECLAIM_MASK; va = kmem_cache_alloc_node(vmap_area_cachep, gfp_mask, node); if (unlikely(!va)) @@ -2057,8 +2061,14 @@ static struct vmap_area *alloc_vmap_area(unsigned long size, * If an allocation fails, the error value is * returned. Therefore trigger the overflow path. */ - if (IS_ERR_VALUE(addr)) + if (IS_ERR_VALUE(addr)) { + if (!allow_block) { + kmem_cache_free(vmap_area_cachep, va); + return ERR_PTR(-ENOMEM); + } + goto overflow; + } va->va_start = addr; va->va_end = addr + size; -- 2.39.5