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Thu, 29 Aug 2024 10:51:28 +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 kpD3JbBS0GZ7DQAAD6G6ig (envelope-from ); Thu, 29 Aug 2024 10:51:28 +0000 Received: by quack3.suse.cz (Postfix, from userid 1000) id 5639FA0965; Thu, 29 Aug 2024 12:51:28 +0200 (CEST) Date: Thu, 29 Aug 2024 12:51:28 +0200 From: Jan Kara To: Josef Bacik Cc: kernel-team@fb.com, linux-fsdevel@vger.kernel.org, jack@suse.cz, amir73il@gmail.com, brauner@kernel.org, linux-xfs@vger.kernel.org, gfs2@lists.linux.dev, linux-bcachefs@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v4 12/16] mm: don't allow huge faults for files with pre content watches Message-ID: <20240829105128.zvczpadmdoaarau2@quack3> References: Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Spam-Level: X-Spamd-Result: default: False [-3.80 / 50.00]; BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_RHS_NOT_FQDN(0.50)[]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; MISSING_XM_UA(0.00)[]; RCPT_COUNT_SEVEN(0.00)[10]; MIME_TRACE(0.00)[0:+]; RCVD_COUNT_THREE(0.00)[3]; FREEMAIL_ENVRCPT(0.00)[gmail.com]; DKIM_SIGNED(0.00)[suse.cz:s=susede2_rsa,suse.cz:s=susede2_ed25519]; FROM_HAS_DN(0.00)[]; FREEMAIL_CC(0.00)[fb.com,vger.kernel.org,suse.cz,gmail.com,kernel.org,lists.linux.dev,kvack.org]; TO_DN_SOME(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; RCVD_TLS_LAST(0.00)[]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FUZZY_BLOCKED(0.00)[rspamd.com]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,toxicpanda.com:email,suse.com:email] X-Spam-Score: -3.80 X-Spam-Flag: NO On Wed 14-08-24 17:25:30, Josef Bacik wrote: > There's nothing stopping us from supporting this, we could simply pass > the order into the helper and emit the proper length. However currently > there's no tests to validate this works properly, so disable it until > there's a desire to support this along with the appropriate tests. > > Reviewed-by: Christian Brauner > Signed-off-by: Josef Bacik Looks good to me. I don't expect this to be controversial but let's CC MM guys for awareness... Honza > --- > mm/memory.c | 22 ++++++++++++++++++++++ > 1 file changed, 22 insertions(+) > > diff --git a/mm/memory.c b/mm/memory.c > index d10e616d7389..3010bcc5e4f9 100644 > --- a/mm/memory.c > +++ b/mm/memory.c > @@ -78,6 +78,7 @@ > #include > #include > #include > +#include > > #include > > @@ -5252,8 +5253,17 @@ static vm_fault_t do_numa_page(struct vm_fault *vmf) > static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf) > { > struct vm_area_struct *vma = vmf->vma; > + struct file *file = vma->vm_file; > if (vma_is_anonymous(vma)) > return do_huge_pmd_anonymous_page(vmf); > + /* > + * Currently we just emit PAGE_SIZE for our fault events, so don't allow > + * a huge fault if we have a pre content watch on this file. This would > + * be trivial to support, but there would need to be tests to ensure > + * this works properly and those don't exist currently. > + */ > + if (file && fsnotify_file_has_pre_content_watches(file)) > + return VM_FAULT_FALLBACK; > if (vma->vm_ops->huge_fault) > return vma->vm_ops->huge_fault(vmf, PMD_ORDER); > return VM_FAULT_FALLBACK; > @@ -5263,6 +5273,7 @@ static inline vm_fault_t create_huge_pmd(struct vm_fault *vmf) > static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf) > { > struct vm_area_struct *vma = vmf->vma; > + struct file *file = vma->vm_file; > const bool unshare = vmf->flags & FAULT_FLAG_UNSHARE; > vm_fault_t ret; > > @@ -5277,6 +5288,9 @@ static inline vm_fault_t wp_huge_pmd(struct vm_fault *vmf) > } > > if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) { > + /* See comment in create_huge_pmd. */ > + if (file && fsnotify_file_has_pre_content_watches(file)) > + goto split; > if (vma->vm_ops->huge_fault) { > ret = vma->vm_ops->huge_fault(vmf, PMD_ORDER); > if (!(ret & VM_FAULT_FALLBACK)) > @@ -5296,9 +5310,13 @@ static vm_fault_t create_huge_pud(struct vm_fault *vmf) > #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \ > defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) > struct vm_area_struct *vma = vmf->vma; > + struct file *file = vma->vm_file; > /* No support for anonymous transparent PUD pages yet */ > if (vma_is_anonymous(vma)) > return VM_FAULT_FALLBACK; > + /* See comment in create_huge_pmd. */ > + if (file && fsnotify_file_has_pre_content_watches(file)) > + return VM_FAULT_FALLBACK; > if (vma->vm_ops->huge_fault) > return vma->vm_ops->huge_fault(vmf, PUD_ORDER); > #endif /* CONFIG_TRANSPARENT_HUGEPAGE */ > @@ -5310,12 +5328,16 @@ static vm_fault_t wp_huge_pud(struct vm_fault *vmf, pud_t orig_pud) > #if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \ > defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) > struct vm_area_struct *vma = vmf->vma; > + struct file *file = vma->vm_file; > vm_fault_t ret; > > /* No support for anonymous transparent PUD pages yet */ > if (vma_is_anonymous(vma)) > goto split; > if (vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) { > + /* See comment in create_huge_pmd. */ > + if (file && fsnotify_file_has_pre_content_watches(file)) > + goto split; > if (vma->vm_ops->huge_fault) { > ret = vma->vm_ops->huge_fault(vmf, PUD_ORDER); > if (!(ret & VM_FAULT_FALLBACK)) > -- > 2.43.0 > -- Jan Kara SUSE Labs, CR