From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx140.postini.com [74.125.245.140]) by kanga.kvack.org (Postfix) with SMTP id F2D166B0072 for ; Fri, 26 Oct 2012 09:40:37 -0400 (EDT) Date: Fri, 26 Oct 2012 16:41:29 +0300 From: "Kirill A. Shutemov" Subject: Re: [PATCH 1/2] numa, mm: drop redundant check in do_huge_pmd_numa_page() Message-ID: <20121026134129.GA31306@otc-wbsnb-06> References: <1351256077-1594-1-git-send-email-kirill.shutemov@linux.intel.com> <1351256885.16863.62.camel@twins> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="SLDf9lqlvOQaIe6s" Content-Disposition: inline In-Reply-To: <1351256885.16863.62.camel@twins> Sender: owner-linux-mm@kvack.org List-ID: To: Peter Zijlstra Cc: linux-mm@kvack.org, Will Deacon , Andrew Morton , Andrea Arcangeli , Xiao Guangrong , Ingo Molnar , linux-kernel@vger.kernel.org --SLDf9lqlvOQaIe6s Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Fri, Oct 26, 2012 at 03:08:05PM +0200, Peter Zijlstra wrote: > On Fri, 2012-10-26 at 15:54 +0300, Kirill A. Shutemov wrote: > > From: "Kirill A. Shutemov" > >=20 > > We check if the pmd entry is the same as on pmd_trans_huge() in > > handle_mm_fault(). That's enough. > >=20 > > Signed-off-by: Kirill A. Shutemov >=20 > Ah indeed, Will mentioned something like this on IRC as well, I hadn't > gotten around to looking at it -- now have, thanks! >=20 > Acked-by: Peter Zijlstra >=20 > That said, where in handle_mm_fault() do we wait for a split to > complete? We have a pmd_trans_huge() && !pmd_trans_splitting(), so a > fault on a currently splitting pmd will fall through. >=20 > Is it the return from the fault on unlikely(pmd_trans_huge()) ? Yes, this code will catch it: /* if an huge pmd materialized from under us just retry later */ if (unlikely(pmd_trans_huge(*pmd))) return 0; If the pmd is under splitting it's still a pmd_trans_huge(). --=20 Kirill A. Shutemov --SLDf9lqlvOQaIe6s Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJQipMJAAoJEAd+omnVudOM8j8P/jV7FrXY1JE5OmKg6Po19tiD k0TGEYfJvgmpmyX6eNwutMUkZFXit8zBVnqXXLW9RTQivVn/EPRopbh05eq7ulUU +0i6jNvyrbUaxk7PviW+iejfEkMVlVSOcP4DxRTr8g4LsJmTceKrnCSJCi3mOGj1 Ls9OBxN828xrlSo5d2yX6Keg6TMQL4Ij3fU49cDDruIstcrRQzgq5OLkEK2UDHBY cvHD4w8ef92eV+x1Z2bj2FITRcEg7oyYkMLretQs7pv+QwfazfRiScGd08pz5uk4 VXplZI55HpqnMElKluYt5LyFvi1pTf0yM7hOulCbb2DXiSciO6WX6hQ0Baljn6t8 WDQ6CkqGgLM3zbicqcfXksv7ST5GJmH9bZuUuhKjjzACMjqgawfombAKBgHWVApo Q1K91tmUmfYtsakRos4ChbyAjIgg7iUqpGQ9uYNnjEegMgTvdp0OIO3QygbI2IcW 3mmjcbiAWr6J9bbaZ1+cYAt8S0QM8ZXm6dvpLCqYG/6TMsjRNsqpv05GCmDHpX+T LbBxHA+CaUHMBhPTriDflJFyL2AuUiOTXiNYueD0qQmAGDpfG1I+GI6B0GZwmM8o HT86DFvoxi0l0JLi8lmrgNve6LT7890i8foavFPAGPTTpK2YIQztKtv8TT1spJ9u 4p85DVfL0h+R2OdAIOZw =wObX -----END PGP SIGNATURE----- --SLDf9lqlvOQaIe6s-- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org