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charset="utf-8" Content-Transfer-Encoding: 7bit X-B4-Tracking: v=1; b=H4sIAEC1rmkC/3XMQQ7CIBCF4as0rMUMU8TqynsYF7QFmVjBgCFq0 7tLu9IYl/9L3jeyZCKZxPbVyKLJlCj4EvWqYp3T/mw49aUZAiqoAXm+6mEIHU8ukr9wkC1arZp GC8nK6RaNpccCHk+lHaV7iM/Fz2Je/1JZcOBS9cZaqTbt1hxewYWrpmFNns1Yxk9A/gBYAGw63 IlegQD4BqZpegNFkO427wAAAA== X-Change-ID: 20260302-vmalloc-shrink-04b2fa688a14 To: Andrew Morton , Uladzislau Rezki Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Alice Ryhl , Danilo Krummrich , Shivam Kalra X-Mailer: b4 0.14.3 X-Developer-Signature: v=1; a=ed25519-sha256; t=1773057354; l=2366; i=shivamkalra98@zohomail.in; s=20260212; h=from:subject:message-id; bh=jlu8U+9Fzz1mb0zaTPT4T2YTs5PlfD7vbOcNzJEvn7w=; b=5pgfQzbKvodieJzhPogRQRGbYfEQ4jxUYsqRmvYl16Gp94uAeLz/QVgaiz2d8T1KReTIewEJc x3Oe+2Rl5UwCpZL+iiw47sfuk6P0adKOWiCAqe6v0Y+zRc+tBLgwMy5 X-Developer-Key: i=shivamkalra98@zohomail.in; a=ed25519; pk=9Q+S1LD/xjbjL7bEaLIlwRADBwU/6LJq7lYm8LFrkQE= X-Endpoint-Received: by B4 Relay for shivamkalra98@zohomail.in/20260212 with auth_id=633 X-Original-From: Shivam Kalra Reply-To: shivamkalra98@zohomail.in X-Stat-Signature: uekow9zzyr3nhesibriumhrb69ee8995 X-Rspamd-Server: rspam09 X-Rspam-User: X-Rspamd-Queue-Id: 4C5F5C0003 X-HE-Tag: 1773057357-894305 X-HE-Meta: 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 OZXS2D7U ZJ6Wqeid1Rj2fm6vNiCcVBlYUSAp7NkDINKERN28ZqFgMmo9IgIAks5vI1hHgKbsgvv4aRdwIw93XSUw/6eIU5zw33Zb9NSZPx06pFv+jcwbuM8wF4XtohDDSP3cRydk4FV4Ggd07LhrBkJSadbo3jXkVKVsK883dFwLqGzHGgoTDNPXW7YJSP+SFW7YnXp7C13CHaOXPczBJ+nM6yztwkGa2EVUawyMTuOHl1JaxdP9EQiDRm2NQP0dYcz4Y8OhOFgfaH6RXYAg+WxXY0y+0+dHhqyUbtfcXLw21dfJZYqOy18vmDFKZwsB1fKZXvYCTZ62DlsBdGhHL74m/RT+tgy3sYWiNoC1apIaPv++85l5wt6hzJdaGMykgUmGcj8R7INlChnaljTaGhS8= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: This series implements the TODO in vrealloc() to unmap and free unused pages when shrinking across a page boundary. Problem: When vrealloc() shrinks an allocation, it updates bookkeeping (requested_size, KASAN shadow) but does not free the underlying physical pages. This wastes memory for the lifetime of the allocation. Solution: - Patch 1: Extracts a vmalloc_free_pages(vm, start, end) helper from vfree() that frees a range of pages with memcg and nr_vmalloc_pages accounting. Pure refactor, no functional change. - Patch 2: Uses the helper to free tail pages when vrealloc() shrinks across a page boundary. Skips huge page allocations (page_order > 0) since compound pages cannot be partially freed. Also fixes the grow-in-place path to check vm->nr_pages instead of get_vm_area_size(), which reflects the virtual reservation and does not change on shrink. The virtual address reservation is kept intact to preserve the range for potential future grow-in-place support. A concrete user is the Rust binder driver's KVVec::shrink_to [1], which performs explicit vrealloc() shrinks for memory reclamation. Tested: - KASAN KUnit (vmalloc_oob passes) - lib/test_vmalloc stress tests (3/3, 1M iterations each) - checkpatch, sparse, W=1, allmodconfig, coccicheck clean [1] https://lore.kernel.org/all/20260216-binder-shrink-vec-v3-v6-0-ece8e8593e53@zohomail.in/ Signed-off-by: Shivam Kalra --- Changes in v3: - Restore the comment. - Rebase to the latest mm-new - Link to v2: https://lore.kernel.org/r/20260304-vmalloc-shrink-v2-0-28c291d60100@zohomail.in Changes in v2: - Updated the base-commit to mm-new - Fix conflicts after rebase - Ran `clang-format` on the changes made - Use a single `kasan_vrealloc` (Alice Ryhl) - Link to v1: https://lore.kernel.org/r/20260302-vmalloc-shrink-v1-0-46deff465b7e@zohomail.in --- Shivam Kalra (2): mm/vmalloc: extract vmalloc_free_pages() helper from vfree() mm/vmalloc: free unused pages on vrealloc() shrink mm/vmalloc.c | 65 ++++++++++++++++++++++++++++++++++++++++++------------------ 1 file changed, 46 insertions(+), 19 deletions(-) --- base-commit: f27e4dd73ee9b64177649a1490fa20288e0de94a change-id: 20260302-vmalloc-shrink-04b2fa688a14 Best regards, -- Shivam Kalra