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Tue, 10 Nov 2026 18:26:19 -0800 (PST) Received: from ryzen.lan ([2601:644:8000:37f::e34]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3b17db56c7esm2040066a91.8.2026.11.10.18.26.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Nov 2026 18:26:18 -0800 (PST) From: Rosen Penev To: Masami Hiramatsu , Oleg Nesterov , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Namhyung Kim Cc: Mark Rutland , Alexander Shishkin , Jiri Olsa , Ian Rogers , Adrian Hunter , James Clark , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: [PATCH v2] uprobes: Use flexible array for xol_area bitmap Date: Tue, 10 Nov 2026 18:26:05 -0800 Message-ID: <20261111022605.66010-1-rosenp@gmail.com> X-Mailer: git-send-email 2.56.0 X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The XOL slot bitmap has the same lifetime as struct xol_area, but it is currently allocated separately. That adds another allocation failure path and a matching cleanup branch without buying any extra flexibility. Store the bitmap as a flexible array member and allocate it together with the xol_area using kzalloc_flex(). The bitmap remains zero-initialized, while the allocation and error handling become simpler. Signed-off-by: Rosen Penev Acked-by: Masami Hiramatsu (Google) --- v2: add Acked-by. remove Assisted-by kernel/events/uprobes.c | 14 +++----------- 1 file changed, 3 insertions(+), 11 deletions(-) diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 853fc952331c..876c3cfe8031 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -108,7 +108,6 @@ static LIST_HEAD(delayed_uprobe_list); */ struct xol_area { wait_queue_head_t wq; /* if all slots are busy */ - unsigned long *bitmap; /* 0 = free slot */ struct page *page; /* @@ -117,6 +116,7 @@ struct xol_area { * the vma go away, and we must handle that reasonably gracefully. */ unsigned long vaddr; /* Page(s) of instruction slots */ + unsigned long bitmap[]; /* 0 = free slot */ }; static void uprobe_warn(struct task_struct *t, const char *msg) @@ -1760,18 +1760,13 @@ static struct xol_area *__create_xol_area(unsigned long vaddr) struct xol_area *area; void *insns; - area = kzalloc_obj(*area); + area = kzalloc_flex(*area, bitmap, BITS_TO_LONGS(UINSNS_PER_PAGE)); if (unlikely(!area)) goto out; - area->bitmap = kcalloc(BITS_TO_LONGS(UINSNS_PER_PAGE), sizeof(long), - GFP_KERNEL); - if (!area->bitmap) - goto free_area; - area->page = alloc_page(GFP_HIGHUSER | __GFP_ZERO); if (!area->page) - goto free_bitmap; + goto free_area; area->vaddr = vaddr; init_waitqueue_head(&area->wq); @@ -1784,8 +1779,6 @@ static struct xol_area *__create_xol_area(unsigned long vaddr) return area; __free_page(area->page); - free_bitmap: - kfree(area->bitmap); free_area: kfree(area); out: @@ -1826,7 +1819,6 @@ void uprobe_clear_state(struct mm_struct *mm) return; put_page(area->page); - kfree(area->bitmap); kfree(area); } -- 2.56.0