From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Naoya Horiguchi To: Dan Williams CC: "linux-nvdimm@lists.01.org" , "hch@lst.de" , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" , "linux-kernel@vger.kernel.org" , "jack@suse.cz" , "ross.zwisler@linux.intel.com" Subject: Re: [PATCH v5 06/11] mm, memory_failure: Collect mapping size in collect_procs() Date: Fri, 13 Jul 2018 06:49:16 +0000 Message-ID: <20180713064916.GB10034@hori1.linux.bs1.fc.nec.co.jp> References: <153074042316.27838.17319837331947007626.stgit@dwillia2-desk3.amr.corp.intel.com> <153074045526.27838.11460088022513024933.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: <153074045526.27838.11460088022513024933.stgit@dwillia2-desk3.amr.corp.intel.com> Content-Language: ja-JP Content-Type: text/plain; charset="iso-2022-jp" Content-ID: <91675B8EB5C02F4A93C6F4133359C60B@gisp.nec.co.jp> Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Sender: owner-linux-mm@kvack.org List-ID: On Wed, Jul 04, 2018 at 02:40:55PM -0700, Dan Williams wrote: > In preparation for supporting memory_failure() for dax mappings, teach > collect_procs() to also determine the mapping size. Unlike typical > mappings the dax mapping size is determined by walking page-table > entries rather than using the compound-page accounting for THP pages. >=20 > Cc: Naoya Horiguchi > Signed-off-by: Dan Williams Looks good to me. Acked-by: Naoya Horiguchi > --- > mm/memory-failure.c | 81 +++++++++++++++++++++++++--------------------= ------ > 1 file changed, 40 insertions(+), 41 deletions(-) >=20 > diff --git a/mm/memory-failure.c b/mm/memory-failure.c > index 9d142b9b86dc..4d70753af59c 100644 > --- a/mm/memory-failure.c > +++ b/mm/memory-failure.c > @@ -174,22 +174,51 @@ int hwpoison_filter(struct page *p) > EXPORT_SYMBOL_GPL(hwpoison_filter); > =20 > /* > + * Kill all processes that have a poisoned page mapped and then isolate > + * the page. > + * > + * General strategy: > + * Find all processes having the page mapped and kill them. > + * But we keep a page reference around so that the page is not > + * actually freed yet. > + * Then stash the page away > + * > + * There's no convenient way to get back to mapped processes > + * from the VMAs. So do a brute-force search over all > + * running processes. > + * > + * Remember that machine checks are not common (or rather > + * if they are common you have other problems), so this shouldn't > + * be a performance issue. > + * > + * Also there are some races possible while we get from the > + * error detection to actually handle it. > + */ > + > +struct to_kill { > + struct list_head nd; > + struct task_struct *tsk; > + unsigned long addr; > + short size_shift; > + char addr_valid; > +}; > + > +/* > * Send all the processes who have the page mapped a signal. > * ``action optional'' if they are not immediately affected by the error > * ``action required'' if error happened in current execution context > */ > -static int kill_proc(struct task_struct *t, unsigned long addr, > - unsigned long pfn, struct page *page, int flags) > +static int kill_proc(struct to_kill *tk, unsigned long pfn, int flags) > { > - short addr_lsb; > + struct task_struct *t =3D tk->tsk; > + short addr_lsb =3D tk->size_shift; > int ret; > =20 > pr_err("Memory failure: %#lx: Killing %s:%d due to hardware memory corr= uption\n", > pfn, t->comm, t->pid); > - addr_lsb =3D compound_order(compound_head(page)) + PAGE_SHIFT; > =20 > if ((flags & MF_ACTION_REQUIRED) && t->mm =3D=3D current->mm) { > - ret =3D force_sig_mceerr(BUS_MCEERR_AR, (void __user *)addr, > + ret =3D force_sig_mceerr(BUS_MCEERR_AR, (void __user *)tk->addr, > addr_lsb, current); > } else { > /* > @@ -198,7 +227,7 @@ static int kill_proc(struct task_struct *t, unsigned = long addr, > * This could cause a loop when the user sets SIGBUS > * to SIG_IGN, but hopefully no one will do that? > */ > - ret =3D send_sig_mceerr(BUS_MCEERR_AO, (void __user *)addr, > + ret =3D send_sig_mceerr(BUS_MCEERR_AO, (void __user *)tk->addr, > addr_lsb, t); /* synchronous? */ > } > if (ret < 0) > @@ -235,35 +264,6 @@ void shake_page(struct page *p, int access) > EXPORT_SYMBOL_GPL(shake_page); > =20 > /* > - * Kill all processes that have a poisoned page mapped and then isolate > - * the page. > - * > - * General strategy: > - * Find all processes having the page mapped and kill them. > - * But we keep a page reference around so that the page is not > - * actually freed yet. > - * Then stash the page away > - * > - * There's no convenient way to get back to mapped processes > - * from the VMAs. So do a brute-force search over all > - * running processes. > - * > - * Remember that machine checks are not common (or rather > - * if they are common you have other problems), so this shouldn't > - * be a performance issue. > - * > - * Also there are some races possible while we get from the > - * error detection to actually handle it. > - */ > - > -struct to_kill { > - struct list_head nd; > - struct task_struct *tsk; > - unsigned long addr; > - char addr_valid; > -}; > - > -/* > * Failure handling: if we can't find or can't kill a process there's > * not much we can do. We just print a message and ignore otherwise. > */ > @@ -292,6 +292,7 @@ static void add_to_kill(struct task_struct *tsk, stru= ct page *p, > } > tk->addr =3D page_address_in_vma(p, vma); > tk->addr_valid =3D 1; > + tk->size_shift =3D compound_order(compound_head(p)) + PAGE_SHIFT; > =20 > /* > * In theory we don't have to kill when the page was > @@ -317,9 +318,8 @@ static void add_to_kill(struct task_struct *tsk, stru= ct page *p, > * Also when FAIL is set do a force kill because something went > * wrong earlier. > */ > -static void kill_procs(struct list_head *to_kill, int forcekill, > - bool fail, struct page *page, unsigned long pfn, > - int flags) > +static void kill_procs(struct list_head *to_kill, int forcekill, bool fa= il, > + unsigned long pfn, int flags) > { > struct to_kill *tk, *next; > =20 > @@ -342,8 +342,7 @@ static void kill_procs(struct list_head *to_kill, int= forcekill, > * check for that, but we need to tell the > * process anyways. > */ > - else if (kill_proc(tk->tsk, tk->addr, > - pfn, page, flags) < 0) > + else if (kill_proc(tk, pfn, flags) < 0) > pr_err("Memory failure: %#lx: Cannot send advisory machine check sig= nal to %s:%d\n", > pfn, tk->tsk->comm, tk->tsk->pid); > } > @@ -1012,7 +1011,7 @@ static bool hwpoison_user_mappings(struct page *p, = unsigned long pfn, > * any accesses to the poisoned memory. > */ > forcekill =3D PageDirty(hpage) || (flags & MF_MUST_KILL); > - kill_procs(&tokill, forcekill, !unmap_success, p, pfn, flags); > + kill_procs(&tokill, forcekill, !unmap_success, pfn, flags); > =20 > return unmap_success; > } >=20 > =