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h=Date:From:To:Cc:Subject:References:In-Reply-To; b=mb9BXWxt88MpB9qYnzbH95e1QrRQzxEiEgi7/2F/8hxj4Nvv6oj2/BHBk3Qm4gqWL GWeQP4oq2b0cRa2vq/YWt+VON52QmcgZEKdFhblV4sG21cPhx+3wEiJL7g1rSNBGWZ DOZEbwSUVAdSZaOr+LHmaj0c+P27fOkNdwnZBKUVKBPukBo5ykBFnYtk4P3++breFR YZGcdhdHz4Cl+8ot9hRaARiYvlfxC5HqpAX3YTCviIkNyGZ8iborIKNboR1PAQKiyL zuVTGaL39gigLDweKWhWXmrbSyUlNv6nhWP+3qMkdZIIEuciRIZYaqsahz6mAOn8+W LWEfQ2qVRcwDw== Date: Sun, 18 Oct 2026 07:31:25 +0300 From: Mike Rapoport To: Federico Parola Cc: stable@vger.kernel.org, Pasha Tatashin , Pratyush Yadav , Alexander Graf , Andrew Morton , kexec@lists.infradead.org, linux-mm@kvack.org, nh-open-source@amazon.com Subject: Re: [PATCH 6.18.y 2/2] kho: free phys_bits bitmaps using free_page() in __kho_abort() Message-ID: References: <20261015144529.76911-1-fparola@amazon.de> <20261015144529.76911-3-fparola@amazon.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261015144529.76911-3-fparola@amazon.de> X-Rspamd-Server: rspam03 X-Rspam-User: X-Rspamd-Queue-Id: C432E100003 X-Stat-Signature: ckp516s7pujuyxdwky3ktopa3ikbprzs X-HE-Tag: 1792297893-345795 X-HE-Meta: U2FsdGVkX1+rEkfWEVOdGqrJPZAq7NEW86vK9b+pM/+rKTz8/S7D/7MyaluFZm1ZC14gZ5dm60ZeGfw9XJJS05XAp0DZfri+86Jsw963iQYpgaOqw26/i8PwU01YPHb3loSeYOoy2PlIbDipCCv1Tszv34KnKhy2dfaGSHyI4XQfad/mTOvUzADTlCuTdae3k6B94at3ePeXEGffEDKfXr1RkLTaG9QE62CfTrL5wfc/+Nf+Aaf8vw5YioJddbmY3wOczy+nJr2weuKbQhkXYj4G9J3Hz2JoqUotoKXARlMwedFsXesiNzeG5nt3VjsKuB4afXxVm3WtsIXkkE1PVB/bA0nuZ6iuaz2YM/uBxv0Wj9lCsBkZ8brOWHW3rCF/YaqcOPvFAwWL4YZvx0t1OMhUpimp6hm6NIe/hj7vewX2CSvzh5vbiUS/FuDG5Vnf5cpEgP6Ap02zEOQfQUb7dZQ+OYMTDeUenjgyQkphj/4rUcCZO8qC/A9iCA8NPtFxcTl6zDkNaOijzWQw7qoWXJ0ZDgF0p2EsIdPmacWvob7KUJcqZ2YDOYX/Sr8Z/VkhlUJJANvZnBfV2cW+rgFOQPV/hH68hZMbtKabPTEUVaKru/LXlKtX6hN2b0W66fMSPIXCQklfq2cXlMONjpbYZiHPBs2f/1rUmhcERHjLc0lLDvgFWPO1rqWn0PbDb8gVvYBtSyzXQRYPEcYuhDMwZ2pOA3OTpNm+Gw6SdN4rDTRyW8VcMy63TWAv9wl5QPwgpKUClrj+stTsK1/k+2sObgLXkQAdQghoaOyTmXms3U/j2a+VZiMCRjWf2mqTVhUfeKZYgp/yd9u6qF+tiqmWvcShyu6RCY8qM6UiZQ6h7a/CfAnq4m2p8ocBdIcIyq1U0FGD9Yhpw1KaPQftZFXY+k/eNZcgtIbN1E84ZptTtP8dFXVEalELj2VjLgwScT0MuzAnINI/3bDJzKMgTY7 S8r+RAWg Op2JJH20MOfr6AR8ZdIOqPSyGhFpBBcyqXXrNZGp3jun8lSibCm39aHPcEyoDTPsyrIlid+zLma2mnRXZyWrvl7FKmsZHIRX32/ea3vDhN0IuU3cyZuwn7FW/ISEM9Fj97Y4jWsvPD3AWjj02popu3723ZlvFqfvwMWNJm4psGTkfFEdWjpmAyGrls7/rDciyWhUX5DfYIl3fridFIRIEO0fehZFnnFJ3FqS+lZrX8Z8/huZUVG/hrW5FVDqIxmlAtoZq585B4R3w94SUTsuVUnC0mE7nFj6L0tjVBKHYiN/UPzbiCJ/DNXIyeKYqbSCiLhFv Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Oct 15, 2026 at 02:45:29PM +0000, Federico Parola wrote: > Commit fa759cd75bce ("kho: allocate metadata directly from the buddy > allocator") switched the allocation of preserved memory bitmaps to > get_zeroed_page(), but __kho_abort() still releases them with kfree(). > kfree() on a buddy page that is not a large kmalloc allocation hits the > WARN_ON_ONCE() in free_large_kmalloc() and returns without freeing it, > so every aborted finalization leaks all bitmap pages. > > Free the bitmaps with free_page() instead. > > This is a stable-only patch. Upstream fixed it as a side effect of > commit 99cd2ffac697 ("kho: don't unpreserve memory during abort"), which > removes the tracking teardown from __kho_abort() altogether. That change > builds on commit 36f8f7ef7fd2 ("kho: add interfaces to unpreserve > folios, page ranges, and vmalloc") and commit 70f9133096c8 ("kho: drop > notifiers"). In 6.18.y, KHO users still preserve memory from the > KEXEC_KHO_FINALIZE notifier and have no interface to unpreserve it, so > the teardown on abort is the only way their preservations get dropped. > Backporting that commit would make preservations outlive every abort, > so keep the teardown and fix only the mismatched free. > > Fixes: fa759cd75bce ("kho: allocate metadata directly from the buddy allocator") > Signed-off-by: Federico Parola Acked-by: Mike Rapoport (Microsoft) > --- > kernel/kexec_handover.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/kernel/kexec_handover.c b/kernel/kexec_handover.c > index 9fe5d14f1ec54..9691f6bc2fba7 100644 > --- a/kernel/kexec_handover.c > +++ b/kernel/kexec_handover.c > @@ -1054,7 +1054,7 @@ static int __kho_abort(void) > unsigned long phys; > > xa_for_each(&physxa->phys_bits, phys, bits) > - kfree(bits); > + free_page((unsigned long)bits); > > xa_destroy(&physxa->phys_bits); > kfree(physxa); > -- > 2.47.3 > -- Sincerely yours, Mike.