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bh=wB9yo6B995pyR1WHngI60PKsDG18PMwNpyYk7BknREA=; b=BLTDQuj3MZ2muMWqRkHBIW8Wc9czA2FSoHg2hbJ7DeaKUy5xvPRA53Uevy6Q/IKQCHb3iS EPldRwmnVHzIY6Dg== Received: from imap1.dmz-prg2.suse.org (localhost [127.0.0.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by imap1.dmz-prg2.suse.org (Postfix) with ESMTPS id DDF8413A1E; Tue, 21 May 2024 07:35:03 +0000 (UTC) Received: from dovecot-director2.suse.de ([2a07:de40:b281:106:10:150:64:167]) by imap1.dmz-prg2.suse.org with ESMTPSA id totQM6dOTGZSfQAAD6G6ig (envelope-from ); Tue, 21 May 2024 07:35:03 +0000 From: Oscar Salvador To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Muchun Song , Vishal Moola , Oscar Salvador Subject: [PATCH] mm/hugetlb: Move vmf_anon_prepare upfront in hugetlb_wp Date: Tue, 21 May 2024 09:34:46 +0200 Message-ID: <20240521073446.23185-1-osalvador@suse.de> X-Mailer: git-send-email 2.44.0 MIME-Version: 1.0 X-Rspamd-Queue-Id: ED1701A0002 X-Stat-Signature: yts4h9emgkue6sdqrs4ay7at8ikd1mwf X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1716276905-424946 X-HE-Meta: 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 npUYa2Vx ysxvqNRQJgw/CAf4RjYueSR0AE9Hp+v3srjtinxngefwNrrylzyJipuG5NaiY1xsROlLIlNaYsMD8blETBG2xs+SROeEzL+QrAihXsuP6LexdCXg4qteD33Fw72RmiETAoPu9L/KHRcp1AXzJGwRY0XNFvf51cjyd5Mdy60DaoDPiZfUA2/ubiOM/+9zkxk43rbQ0RpJEji1c4Dhcepq62ecLfMmbibtyBeH1TYmAOZavwbTnSmP6/wgbFTXVb4PjlNweLqcaTLIR6wPF6dlOtV+wvOp3zAWjduaBT6z269fOZiAvuouYu00NkbSnYuye8sHsxakIwaiVL/DaCZrII6o3t8TNxudzz9Rc X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: hugetlb_wp calls vmf_anon_prepare() after having allocated a page, which means that we might need to call restore_reserve_on_error() upon error. vmf_anon_prepare() releases the vma lock before returning, but restore_reserve_on_error() expects the vma lock to be held by the caller. Fix it by calling vmf_anon_prepare() before allocating the page. Signed-off-by: Oscar Salvador Fixes: 9acad7ba3e25 ("hugetlb: use vmf_anon_prepare() instead of anon_vma_prepare()") --- I did not hit this bug, I just spotted this because I was looking at hugetlb_wp for some other reason. And I did not want to get creative to see if I could trigger this so I could get a backtrace. My assumption is that we could trigger this if 1) this was a shared mapping, so no anon_vma and 2) we call in GUP code with FOLL_WRITE, which would cause the FLAG_UNSHARE to be passed, so we will end up in hugetlb_wp(). mm/hugetlb.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 6be78e7d4f6e..eb0d8a45505e 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6005,6 +6005,15 @@ static vm_fault_t hugetlb_wp(struct folio *pagecache_folio, * be acquired again before returning to the caller, as expected. */ spin_unlock(vmf->ptl); + + /* + * When the original hugepage is shared one, it does not have + * anon_vma prepared. + */ + ret = vmf_anon_prepare(vmf); + if (unlikely(ret)) + goto out_release_old; + new_folio = alloc_hugetlb_folio(vma, vmf->address, outside_reserve); if (IS_ERR(new_folio)) { @@ -6058,14 +6067,6 @@ static vm_fault_t hugetlb_wp(struct folio *pagecache_folio, goto out_release_old; } - /* - * When the original hugepage is shared one, it does not have - * anon_vma prepared. - */ - ret = vmf_anon_prepare(vmf); - if (unlikely(ret)) - goto out_release_all; - if (copy_user_large_folio(new_folio, old_folio, vmf->real_address, vma)) { ret = VM_FAULT_HWPOISON_LARGE | VM_FAULT_SET_HINDEX(hstate_index(h)); goto out_release_all;