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b=bDYa0m6ymveTw0HTGhDflIHkFJVZ6GnutFwAxlS0dnTV93M0i+vTGPjDB/xLJrUNQ 1a0DPsSCrlJe2SPeOdeGGqCukduQ+BHvb6mMYVy4+V4ZLwJWeT2XDAckf22U215/P7 hUHXF+M1stjZ7/4DPBQw9qxLMfak2L3FlpuRHlpJ+c/2EgbEpz2gLU0GyRgmO92zlA ZNKBf+MuuUntdCZet/bCi1BSWnv0+EUx0ZcJJd6V4JezjZRGitiNmaGuuxRIZk+BGw SHxdlwNKF5h85NTEXdvIIhjzcNbqGPJEdvLZVa73xGq4hC7cfgCi68gUdJfX87c1eO MlaqchPPFVn/Q== Message-ID: <19e428e5-d8bc-4abb-b052-e23442464cba@kernel.org> Date: Wed, 9 Sep 2026 19:23:16 +0200 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 4/5] proc/task_mmu: read proc/pid/smaps_rollup under per-vma lock To: Suren Baghdasaryan , akpm@linux-foundation.org Cc: liam@infradead.org, ljs@kernel.org, vbabka@kernel.org, willy@infradead.org, jannh@google.com, paulmck@kernel.org, pfalcato@suse.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org References: <20260907063918.3432401-1-surenb@google.com> <20260907063918.3432401-5-surenb@google.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 7bit X-Stat-Signature: 93byxpmoobo5b1c6gd36esh8e6cuf6m3 X-Rspam-User: X-Rspamd-Queue-Id: 0638420002 X-Rspamd-Server: rspam03 X-HE-Tag: 1788974602-888370 X-HE-Meta: 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 g9HuVrLe Iz22MxteBpxvQQYYV5TZ+FNLGOEQh9e2b2Gm4gf2EOI2h2SCJskBkH+ewtAav/3FH/KxJysKwSZrub370/If/3K+Mcv/6yiBiayJYTpEBi345Jriqy8rgQFHYCU9M97Plk/ecLqeeIkugWXcVZqzs4rSxvdB0uvBEwS7Vks6b//g0hO9TvBN9FyJLs7/jqiwxAvC6vMWXCg5JTISxvJfiM4lfQw46lk/OBcBdab9R+S9pSAMhqK8ibWMh7iQdDqT0RsrU3nMWkwN/yyjOgn2ihdgEXjzfDIU1XtppBwM3N1D9B7g2mY35EBEV6A== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: > - vma_start = vma->vm_start; > - do { > - smap_gather_stats(priv, vma, &mss, vma->vm_start); > - last_vma_end = vma->vm_end; > + if (!IS_ERR(vma) && vma != get_gate_vma(lock_ctx->mm)) > + vma_start = vma->vm_start; > + > + while (vma) { > + if (IS_ERR(vma)) { > + ret = PTR_ERR(vma); > + goto out_unlock; > + } > + Can we add a comment whey we break (and not e.g., continue) whenw e hit the gate VMA? (I seriously don't kmow ... should I know? :) ) > + if (vma == get_gate_vma(lock_ctx->mm)) > + break; > > /* > - * Release mmap_lock temporarily if someone wants to > - * access it for write request. > + * If after retaking the lock, already reported VMA grew or > + * merged with the next one, smap_gather_stats() will gather > + * stats for the remaining portion by starting at last_vma_end. > */ > - if (mmap_lock_is_contended(mm)) { > - vma_iter_invalidate(&vmi); > - unlock_ctx_mm(&priv->lock_ctx); > - ret = lock_ctx_mm(&priv->lock_ctx); > - if (ret) { > - release_task_mempolicy(priv); > - goto out_put_mm; > - } > + smap_gather_stats(priv, vma, &mss, last_vma_end); > + last_vma_end = vma->vm_end; I skimmed over the remaining bits, hoping the VMA lock experts will review in detail :) -- Cheers, David