From: Rik van Riel <riel@surriel.com>
To: linux-kernel@vger.kernel.org
Cc: Rik van Riel <riel@surriel.com>,
x86@kernel.org, linux-mm@kvack.org,
"Thomas Gleixner" <tglx@kernel.org>,
"Ingo Molnar" <mingo@redhat.com>,
"Dmitry Ilvokhin" <d@ilvokhin.com>,
"Borislav Petkov" <bp@alien8.de>,
"Dave Hansen" <dave.hansen@linux.intel.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"David Hildenbrand" <david@kernel.org>,
"Lorenzo Stoakes" <ljs@kernel.org>,
"Liam R. Howlett" <liam@infradead.org>,
"Vlastimil Babka" <vbabka@kernel.org>,
"Suren Baghdasaryan" <surenb@google.com>,
kernel-team@meta.com
Subject: [PATCH v2 0/3] mm: __access_remote_vm with per-VMA lock
Date: Wed, 24 Jun 2026 21:50:50 -0400 [thread overview]
Message-ID: <20260625015053.2445008-1-riel@surriel.com> (raw)
Sometimes processes can get stuck with the mmap_lock held for
a long time. This slows down, and can even prevent system monitoring
tools from assessing and logging the situation, because they themselves
end up getting stuck on the mmap_lock.
However, with the introduction of per-VMA locks, we can improve the
reliability of system monitoring, and generally speed up __access_remote_vm
under mmap_loc contention, by adding a fast path that does not require
the process-wide mmap_lock.
This fast path is only compiled in and used when it is safe to do so,
meaning a kernel with per-VMA locks, RCU pgae table freeing, the VMA
is not hugetlbfs, iomap, pfnmap, etc...
v2:
- simplify the code, which should be ok because these copies are < PAGE_SIZE
- clean up the code
- fix locking wrt tlb_remove_table_sync_one()
- hopefully address all the other comments
next reply other threads:[~2026-06-25 1:51 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-25 1:50 Rik van Riel [this message]
2026-06-25 1:50 ` [PATCH 1/3] x86/mm: use READ_ONCE/WRITE_ONCE for mm->context.untag_mask Rik van Riel
2026-06-25 1:50 ` [PATCH 2/3] mm/pagewalk: let folio_walk_start() run under the per-VMA lock Rik van Riel
2026-06-25 1:50 ` [PATCH 3/3] mm: read remote memory without the mmap lock where possible Rik van Riel
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