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AJvYcCUldIPcKRlLZ3/LLgB0+sP/+jrmzw7iPsbdbKRnL7XYjiDuZ2Ml3Sa3diEtKf0kk+L02JUSYKY4fg==@kvack.org X-Gm-Message-State: AOJu0YzZsIqQFbmRhVOWDMGp15C2BPhxrZLG7ZJbfiIrqxGP+JmZxMIJ /+24Y1SR3pn5Emy5k//96GITZTiY8nDEHild4HlOstd7cgbM+KacjOupBHqFfl3DLuUSdnsvtMh qt2II+CqY3ofSqKTL2DBM1AL6hRV0uPicB9COto0g X-Gm-Gg: ASbGncteLCRw5sbX/dGasRgB+A0ICCkbqhVpoKx/M3DBD0sybt4anzW1T7UfY2ZnvQZ q1oVPrlqPqXpatSCUVX1PvsaUamMYDSwqyOPjpWavnc8RipbuHM+eeTtlq0sVC+keD+/GxkJd48 0ERNrH493IQrC04ggdkS0fU3MfWvstE9qHhU2RHMbRYyUUGpeFdXlM3MFO3PpyCQJ96qDWPpp5F 4Cwi+u17ebHWI9ThfheFflYBvE3ztpahZMvvA== X-Google-Smtp-Source: AGHT+IH/vu3AEPEMg1lWhWr6c5i1Hk7l+MHr3ajLJbommv99ZScZpBMyjMSwyw60o5voAFBY5O9vUyZH8Zz3a0jPmgA= X-Received: by 2002:a05:622a:646:b0:4b0:85d7:b884 with SMTP id d75a77b69052e-4b0a1f66a26mr272861cf.21.1754505805730; Wed, 06 Aug 2025 11:43:25 -0700 (PDT) MIME-Version: 1.0 References: <20250806155905.824388-1-surenb@google.com> <20250806155905.824388-3-surenb@google.com> <01bedec6-53f8-4c1c-9c47-c943ca0f7b4b@lucifer.local> In-Reply-To: <01bedec6-53f8-4c1c-9c47-c943ca0f7b4b@lucifer.local> From: Suren Baghdasaryan Date: Wed, 6 Aug 2025 11:43:14 -0700 X-Gm-Features: Ac12FXyS4v5I4rD9FZQ1-uYMFEt8OMTd5btwqy6XpYscekLqviMpnC9QC0UOhos Message-ID: Subject: Re: [PATCH v3 2/3] fs/proc/task_mmu: factor out proc_maps_private fields used by PROCMAP_QUERY To: Lorenzo Stoakes Cc: akpm@linux-foundation.org, Liam.Howlett@oracle.com, david@redhat.com, vbabka@suse.cz, peterx@redhat.com, jannh@google.com, hannes@cmpxchg.org, mhocko@kernel.org, paulmck@kernel.org, shuah@kernel.org, adobriyan@gmail.com, brauner@kernel.org, josef@toxicpanda.com, yebin10@huawei.com, linux@weissschuh.net, willy@infradead.org, osalvador@suse.de, andrii@kernel.org, ryan.roberts@arm.com, christophe.leroy@csgroup.eu, tjmercier@google.com, kaleshsingh@google.com, aha310510@gmail.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 6574D1C0008 X-Stat-Signature: izytnwdz9q8xfxqhcgi3coqkz6w3eso5 X-Rspam-User: X-HE-Tag: 1754505807-2306 X-HE-Meta: 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 MZRD1t5b urpoDUV0QjMPFXhsUX0W6fFO7BvrPIHFhjniOuyUuQZ0I/FzZrGi9O1RKh1wu8p9hfNR4QLAYMFzN0KkakOFVIq8LzdSyC87N6sq5W8AysBis2jOquQakcRnvGMM82CyWxZ2O/xkSjbvuWg0bGgH6oI6iEcdFtF9dlRmyAMcgMfVp2+dOiFoXdIAD2qFBgT28Ew4t1uBAQmsXbJXU9DlNiT36mGMTPYwkeVtqfpKOfuZ8nUMWxRATFHjj81IAwoAe8ZR2hBWhS4H50wFA5EtIoWMvqoInMpk2w4n93sUDyhRSxzUTinpgfELMP9irGT1ZjlcburG3UgxRmG4= 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: On Wed, Aug 6, 2025 at 11:04=E2=80=AFAM Lorenzo Stoakes wrote: > > On Wed, Aug 06, 2025 at 08:59:03AM -0700, Suren Baghdasaryan wrote: > > Refactor struct proc_maps_private so that the fields used by PROCMAP_QU= ERY > > ioctl are moved into a separate structure. In the next patch this allow= s > > ioctl to reuse some of the functions used for reading /proc/pid/maps > > without using file->private_data. This prevents concurrent modification > > of file->private_data members by ioctl and /proc/pid/maps readers. > > > > The change is pure code refactoring and has no functional changes. > > > > Signed-off-by: Suren Baghdasaryan > > Reviewed-by: Vlastimil Babka > > --- > > fs/proc/internal.h | 15 ++++++---- > > fs/proc/task_mmu.c | 70 ++++++++++++++++++++++---------------------- > > fs/proc/task_nommu.c | 14 ++++----- > > 3 files changed, 52 insertions(+), 47 deletions(-) > > > > diff --git a/fs/proc/internal.h b/fs/proc/internal.h > > index e737401d7383..d1598576506c 100644 > > --- a/fs/proc/internal.h > > +++ b/fs/proc/internal.h > > @@ -378,16 +378,21 @@ extern void proc_self_init(void); > > * task_[no]mmu.c > > */ > > struct mem_size_stats; > > -struct proc_maps_private { > > - struct inode *inode; > > - struct task_struct *task; > > + > > +struct proc_maps_locking_ctx { > > Decent name :) > > > struct mm_struct *mm; > > - struct vma_iterator iter; > > - loff_t last_pos; > > #ifdef CONFIG_PER_VMA_LOCK > > bool mmap_locked; > > struct vm_area_struct *locked_vma; > > #endif > > +}; > > + > > +struct proc_maps_private { > > + struct inode *inode; > > + struct task_struct *task; > > + struct vma_iterator iter; > > + loff_t last_pos; > > + struct proc_maps_locking_ctx lock_ctx; > > #ifdef CONFIG_NUMA > > struct mempolicy *task_mempolicy; > > #endif > > I was going to ask why we have these in internal.h, but then noticed we h= ave to > have a nommu version of the task_mmu stuff for museum pieces and > why-do-they-exist arches, sigh. > > > diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c > > index ee1e4ccd33bd..45134335e086 100644 > > --- a/fs/proc/task_mmu.c > > +++ b/fs/proc/task_mmu.c > > @@ -132,11 +132,11 @@ static void release_task_mempolicy(struct proc_ma= ps_private *priv) > > > > #ifdef CONFIG_PER_VMA_LOCK > > > > -static void unlock_vma(struct proc_maps_private *priv) > > +static void unlock_vma(struct proc_maps_locking_ctx *lock_ctx) > > { > > - if (priv->locked_vma) { > > - vma_end_read(priv->locked_vma); > > - priv->locked_vma =3D NULL; > > + if (lock_ctx->locked_vma) { > > + vma_end_read(lock_ctx->locked_vma); > > + lock_ctx->locked_vma =3D NULL; > > } > > } > > > > @@ -151,14 +151,14 @@ static inline bool lock_vma_range(struct seq_file= *m, > > * walking the vma tree under rcu read protection. > > */ > > if (m->op !=3D &proc_pid_maps_op) { > > - if (mmap_read_lock_killable(priv->mm)) > > + if (mmap_read_lock_killable(priv->lock_ctx.mm)) > > return false; > > > > - priv->mmap_locked =3D true; > > + priv->lock_ctx.mmap_locked =3D true; > > } else { > > rcu_read_lock(); > > - priv->locked_vma =3D NULL; > > - priv->mmap_locked =3D false; > > + priv->lock_ctx.locked_vma =3D NULL; > > + priv->lock_ctx.mmap_locked =3D false; > > } > > > > return true; > > @@ -166,10 +166,10 @@ static inline bool lock_vma_range(struct seq_file= *m, > > > > static inline void unlock_vma_range(struct proc_maps_private *priv) > > { > > Not sure why we have unlock_vma() parameterised by proc_maps_locking_ctx = but > this is parameerised by proc_maps_private? > > Seems more consistent to have both parameterised by proc_maps_locking_ctx= . True, we can pass just proc_maps_locking_ctx to both lock_vma_range() and unlock_vma_range(). Will update. > > Maybe we'd want lock() forms this way too for consistency? > > > - if (priv->mmap_locked) { > > - mmap_read_unlock(priv->mm); > > + if (priv->lock_ctx.mmap_locked) { > > + mmap_read_unlock(priv->lock_ctx.mm); > > } else { > > - unlock_vma(priv); > > + unlock_vma(&priv->lock_ctx); > > rcu_read_unlock(); > > } > > } > > @@ -179,13 +179,13 @@ static struct vm_area_struct *get_next_vma(struct= proc_maps_private *priv, > > { > > struct vm_area_struct *vma; > > > > We reference priv->lock_ctx 3 times here, either extract as helper var or= pass > in direct perhaps? > > > - if (priv->mmap_locked) > > + if (priv->lock_ctx.mmap_locked) > > return vma_next(&priv->iter); > > > > - unlock_vma(priv); > > - vma =3D lock_next_vma(priv->mm, &priv->iter, last_pos); > > + unlock_vma(&priv->lock_ctx); > > + vma =3D lock_next_vma(priv->lock_ctx.mm, &priv->iter, last_pos); > > if (!IS_ERR_OR_NULL(vma)) > > - priv->locked_vma =3D vma; > > + priv->lock_ctx.locked_vma =3D vma; > > > > return vma; > > } > > @@ -193,14 +193,14 @@ static struct vm_area_struct *get_next_vma(struct= proc_maps_private *priv, > > static inline bool fallback_to_mmap_lock(struct proc_maps_private *pri= v, > > loff_t pos) > > { > > (Also) > > We reference priv->lock_ctx 3 times here, either extract as helper var or= pass > in direct perhaps? > > > - if (priv->mmap_locked) > > + if (priv->lock_ctx.mmap_locked) > > return false; > > > > rcu_read_unlock(); > > - mmap_read_lock(priv->mm); > > + mmap_read_lock(priv->lock_ctx.mm); > > /* Reinitialize the iterator after taking mmap_lock */ > > vma_iter_set(&priv->iter, pos); > > - priv->mmap_locked =3D true; > > + priv->lock_ctx.mmap_locked =3D true; > > > > return true; > > } > > @@ -210,12 +210,12 @@ static inline bool fallback_to_mmap_lock(struct p= roc_maps_private *priv, > > static inline bool lock_vma_range(struct seq_file *m, > > struct proc_maps_private *priv) > > { > > - return mmap_read_lock_killable(priv->mm) =3D=3D 0; > > + return mmap_read_lock_killable(priv->lock_ctx.mm) =3D=3D 0; > > } > > > > static inline void unlock_vma_range(struct proc_maps_private *priv) > > { > > - mmap_read_unlock(priv->mm); > > + mmap_read_unlock(priv->lock_ctx.mm); > > } > > > > static struct vm_area_struct *get_next_vma(struct proc_maps_private *p= riv, > > @@ -258,7 +258,7 @@ static struct vm_area_struct *proc_get_vma(struct s= eq_file *m, loff_t *ppos) > > *ppos =3D vma->vm_end; > > } else { > > *ppos =3D SENTINEL_VMA_GATE; > > - vma =3D get_gate_vma(priv->mm); > > + vma =3D get_gate_vma(priv->lock_ctx.mm); > > } > > > > return vma; > > @@ -278,7 +278,7 @@ static void *m_start(struct seq_file *m, loff_t *pp= os) > > if (!priv->task) > > return ERR_PTR(-ESRCH); > > > > - mm =3D priv->mm; > > + mm =3D priv->lock_ctx.mm; > > if (!mm || !mmget_not_zero(mm)) { > > put_task_struct(priv->task); > > priv->task =3D NULL; > > @@ -318,7 +318,7 @@ static void *m_next(struct seq_file *m, void *v, lo= ff_t *ppos) > > static void m_stop(struct seq_file *m, void *v) > > { > > struct proc_maps_private *priv =3D m->private; > > - struct mm_struct *mm =3D priv->mm; > > + struct mm_struct *mm =3D priv->lock_ctx.mm; > > > > if (!priv->task) > > return; > > @@ -339,9 +339,9 @@ static int proc_maps_open(struct inode *inode, stru= ct file *file, > > return -ENOMEM; > > > > priv->inode =3D inode; > > - priv->mm =3D proc_mem_open(inode, PTRACE_MODE_READ); > > - if (IS_ERR_OR_NULL(priv->mm)) { > > - int err =3D priv->mm ? PTR_ERR(priv->mm) : -ESRCH; > > + priv->lock_ctx.mm =3D proc_mem_open(inode, PTRACE_MODE_READ); > > + if (IS_ERR_OR_NULL(priv->lock_ctx.mm)) { > > + int err =3D priv->lock_ctx.mm ? PTR_ERR(priv->lock_ctx.mm= ) : -ESRCH; > > > > seq_release_private(inode, file); > > return err; > > @@ -355,8 +355,8 @@ static int proc_map_release(struct inode *inode, st= ruct file *file) > > struct seq_file *seq =3D file->private_data; > > struct proc_maps_private *priv =3D seq->private; > > > > - if (priv->mm) > > - mmdrop(priv->mm); > > + if (priv->lock_ctx.mm) > > + mmdrop(priv->lock_ctx.mm); > > > > return seq_release_private(inode, file); > > } > > @@ -610,7 +610,7 @@ static int do_procmap_query(struct proc_maps_privat= e *priv, void __user *uarg) > > if (!!karg.build_id_size !=3D !!karg.build_id_addr) > > return -EINVAL; > > > > - mm =3D priv->mm; > > + mm =3D priv->lock_ctx.mm; > > if (!mm || !mmget_not_zero(mm)) > > return -ESRCH; > > > > @@ -1311,7 +1311,7 @@ static int show_smaps_rollup(struct seq_file *m, = void *v) > > { > > struct proc_maps_private *priv =3D m->private; > > struct mem_size_stats mss =3D {}; > > - struct mm_struct *mm =3D priv->mm; > > + struct mm_struct *mm =3D priv->lock_ctx.mm; > > Nit, but maybe add a > > struct proc_maps_locking_ctx *lock_ctx =3D priv->lock_ctx; > > Here to reduce 'priv->lock_ctx' stuff? Yep, will do that in all the places. Thanks! > > > struct vm_area_struct *vma; > > unsigned long vma_start =3D 0, last_vma_end =3D 0; > > int ret =3D 0; > > @@ -1456,9 +1456,9 @@ static int smaps_rollup_open(struct inode *inode,= struct file *file) > > goto out_free; > > > > priv->inode =3D inode; > > - priv->mm =3D proc_mem_open(inode, PTRACE_MODE_READ); > > - if (IS_ERR_OR_NULL(priv->mm)) { > > - ret =3D priv->mm ? PTR_ERR(priv->mm) : -ESRCH; > > + priv->lock_ctx.mm =3D proc_mem_open(inode, PTRACE_MODE_READ); > > + if (IS_ERR_OR_NULL(priv->lock_ctx.mm)) { > > + ret =3D priv->lock_ctx.mm ? PTR_ERR(priv->lock_ctx.mm) : = -ESRCH; > > > > single_release(inode, file); > > goto out_free; > > @@ -1476,8 +1476,8 @@ static int smaps_rollup_release(struct inode *ino= de, struct file *file) > > struct seq_file *seq =3D file->private_data; > > struct proc_maps_private *priv =3D seq->private; > > > > - if (priv->mm) > > - mmdrop(priv->mm); > > + if (priv->lock_ctx.mm) > > + mmdrop(priv->lock_ctx.mm); > > > > kfree(priv); > > return single_release(inode, file); > > diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c > > index 59bfd61d653a..d362919f4f68 100644 > > --- a/fs/proc/task_nommu.c > > +++ b/fs/proc/task_nommu.c > > @@ -204,7 +204,7 @@ static void *m_start(struct seq_file *m, loff_t *pp= os) > > if (!priv->task) > > return ERR_PTR(-ESRCH); > > > > - mm =3D priv->mm; > > + mm =3D priv->lock_ctx.mm; > > if (!mm || !mmget_not_zero(mm)) { > > put_task_struct(priv->task); > > priv->task =3D NULL; > > @@ -226,7 +226,7 @@ static void *m_start(struct seq_file *m, loff_t *pp= os) > > static void m_stop(struct seq_file *m, void *v) > > { > > struct proc_maps_private *priv =3D m->private; > > - struct mm_struct *mm =3D priv->mm; > > (same as above, I reviewed this upsidedown :P) > > NIT, but seems sensible to have a > > struct proc_maps_locking_ctx *lock_ctx =3D priv->lock_ctx; > > Here so we can avoid the ugly 'priv->lock_ctx' stuff below. > > > + struct mm_struct *mm =3D priv->lock_ctx.mm; > > > > if (!priv->task) > > return; > > @@ -259,9 +259,9 @@ static int maps_open(struct inode *inode, struct fi= le *file, > > return -ENOMEM; > > > > priv->inode =3D inode; > > - priv->mm =3D proc_mem_open(inode, PTRACE_MODE_READ); > > - if (IS_ERR_OR_NULL(priv->mm)) { > > - int err =3D priv->mm ? PTR_ERR(priv->mm) : -ESRCH; > > + priv->lock_ctx.mm =3D proc_mem_open(inode, PTRACE_MODE_READ); > > + if (IS_ERR_OR_NULL(priv->lock_ctx.mm)) { > > + int err =3D priv->lock_ctx.mm ? PTR_ERR(priv->lock_ctx.mm= ) : -ESRCH; > > > > > seq_release_private(inode, file); > > return err; > > @@ -276,8 +276,8 @@ static int map_release(struct inode *inode, struct = file *file) > > struct seq_file *seq =3D file->private_data; > > struct proc_maps_private *priv =3D seq->private; > > > > - if (priv->mm) > > - mmdrop(priv->mm); > > + if (priv->lock_ctx.mm) > > + mmdrop(priv->lock_ctx.mm); > > > > return seq_release_private(inode, file); > > } > > -- > > 2.50.1.565.gc32cd1483b-goog > >